3.Chad Fitzgerald — Direct/Voir Dire (Part 1)

CHAD FITZGERALD: Okay. Chad Fitzgerald, F-I-T-Z-G-E-R-A-L-D.

CHAD FITZGERALD: The Federal Bureau of Investigation, or the FBI, out of Atlanta.

CHAD FITZGERALD: I am.

CHAD FITZGERALD: A little over 18 years.

CHAD FITZGERALD: I'm assigned to the Cellular Analysis Survey Team, or CAST. Our responsibilities include interpreting and analyzing cell phone data as it's received from the different service providers like the AT&Ts and Verizons. And we primarily work on -- we were put in place for child abductions, so we do a lot of -- kind of like a fly team for that, but we also, day to day, do -- help out in local investigations and prosecutions such as murders, robberies. We do bank robberies with the FBI too.

CHAD FITZGERALD: The team started kind of ad hoc several -- about -- I'd say in the neighborhood of eight years ago, and then we became an official unit about five years -- five, six years ago. So we were kind of born out of the fugitive and robbery investigations. A bunch of us were doing phone analysis.

CHAD FITZGERALD: I have, yes.

CHAD FITZGERALD: Going back to school, I have a master's in electrical engineering specializing in communication systems, and since then, being part of this unit, we have been -- we go to training and we meet quite frequently with the different providers in the United States, you know, the Sprint, AT&T, Verizon, Metro PCS and Cricket. I'm sure I'm leaving one out there. But we meet with them, both subpoena compliance and the engineering side, plus we go to specialized training for people that work in that industry, different companies that provide training to the cellular industry and others.

CHAD FITZGERALD: We do both how they maintain their records, but we're also on the side of how their systems are designed -- how the cellular systems are designed and meant to function, everything from RF, radio frequency, to drive testing their networks and how their network is maintaining the records and whatnot.

CHAD FITZGERALD: I did, yes.

CHAD FITZGERALD: My prior employment was Hughes Aircraft Company. I worked as an engineer there doing satellite -- we -- the unit I was assigned to designed hardware for communication to satellite -- command to control of satellites, both commercial -- I mostly worked on the commercial side, but we also had defense satellites, and then I also, before that, have worked at IBM in technical as well as in TV as an engineer.

CHAD FITZGERALD: I have a master's in electrical engineering.

CHAD FITZGERALD: Yes, we -- part of our unit goes around the United States training detectives, police departments, prosecutors. We've had -- we also go overseas and help train investigators overseas just on techniques and methodologies they can use to analyze phone records. I think to date we've trained somewhere in the neighborhood of 6,000. I did about 100 about two weeks ago myself.

CHAD FITZGERALD: Just how we -- in our -- in the CAST unit how we -- what we've done, how we've taken our practical experience as well as our training with all the different providers and the cell technology and we just kind of merge it into a fairly basic two-day class where we teach people the methods we use and the successes we've had using those methods.

CHAD FITZGERALD: Yes.

CHAD FITZGERALD: It gives an interpretation for cell phone data. So somewhere in the neighborhood of more than -- it's 100 to 105 percent of the American population has a cell phone, so that's a very strong tool to be able to exploit when you can receive records. And all the companies do it slightly different, and we just help with that. And it can be quite voluminous, so we just help with techniques to analyze that information and interpret it into, you know, where people can understand it and see what's going on.

CHAD FITZGERALD: Yes. So we do cell site analysis. So the companies have to know -- just by the nature of their business, they have to know the general area of where their phone users are located to deliver and allow them to make calls, and we can take that data and determine the general geographic area of where a phone is located.

CHAD FITZGERALD: Of course, yes. All the time. Every day.

CHAD FITZGERALD: I look at phone records every day. I mean, it's definitely in the thousands, I'm sure.

CHAD FITZGERALD: Yes. So we have a couple of tools we've created on our own with the help of computer programmers as well as just basic, like Micro- -- that people would be familiar with, Microsoft Excel, Google Maps or Google Earth. We also use Microsoft MapPoint, which is the mapping program. So everything from that on up to custom software that we've developed.

CHAD FITZGERALD: Yes. So like I mentioned earlier, we're a pseudo fly team. So if there's a child abduction somewhere in the United States that -- we get involved in quite a bit of those, we will routinely fly either individually or a lot of times as a group to provide coverage and work as a team on the -- you know, there's a lot of records coming in in those, as well as like in this case, we flew up here as soon as we got -- you know, as soon as we knew that we were going to be needed up here.

CHAD FITZGERALD: Yes. So we have -- there will be different assignments within the team to help get through all the data as well as there's also kind of a peer-checking function too where we might be working on the same thing but checking our work also of each other.

CHAD FITZGERALD: Yes, this is the third time in the last week -- the third -- about eight -- between last week and this week, this is the third time in different states -- three different states.

CHAD FITZGERALD: Not -- that's quite a bit, but it definitely -- we fly around and testify a lot in state court, some federal court. But definitely a lot of state court cases. Yes, it's a routine. That's part of the nature of our assignments.

CHAD FITZGERALD: I was, yes.

CHAD FITZGERALD: I was. I came here fairly quickly.

CHAD FITZGERALD: Yes. There were several members here -- both assigned members and people that we have in training, both came here. I'm not sure -- when I was here I think we had somewhere in the neighborhood of five to six people on CAST, and then we got relieved with another wave of people after about a week or so.

CHAD FITZGERALD: Absolutely. I mean, this is pared down to keep it -- try to keep it somewhat simple.

CHAD FITZGERALD: I did, yes.

CHAD FITZGERALD: Yes, that's the first page of my presentation I created.

CHAD FITZGERALD: I hope. That's the purpose of it.

CHAD FITZGERALD: Right. That's our logo, I suppose.

CHAD FITZGERALD: So this is just a photo that I took of a fairly standard cell tower. This is what your phone is ultimately communicating with. There's antennas mounted at the top of -- can I draw on this?

CHAD FITZGERALD: So there's antennas mounted at the top of these triangular structures, are mounted to those triangular structures and pointed in different directions. And that's ultimately what your phone is monitoring. So as my phone sits in my pocket, it's in idle mode, not necessarily doing anything. It's just monitoring the air to see what the strongest, clearest signal is. Typically, it can see multiple different towers, multiple different sectors, which I'll get to. But ultimately, they're communicating with these antennas that are antennas that are mounted at the top of this structure. Those antennas are attached or connected to equipment at the base of this tower, and from there that equipment at the base of the tower is then connected to a switch which is kind of the brains behind the operation. It connects to hundreds, if not thousands, of towers and sectors, and from that switch connected to the rest of the network, Verizon, AT&T network, and then connected to the rest of the world. So I can make and receive a call through that general infrastructure.

CHAD FITZGERALD: Right. So each tower is putting out a signal. And like my phone is only programmed to speak to, you know, a certain set of towers. So my Verizon phone is -- it's no different than a language -- is speaking the Verizon language and only looking for Verizon towers; the AT&T phone is only going to speak to AT&T towers. So they're programmed for certain languages. So like in this instance this particular tower, which is fairly standard, there's multiple layers of antenna on top of it, and, you know, it can be just one company or it can be multiple companies co-located on the same structure.

CHAD FITZGERALD: Well, so my phone will monitor the air and kind of rank the strongest, clearest signal. When I dial a number, hit the green button or hit the send button, my phone will request services from that strongest, clearest signal. So a lot of times I equate it to the teacher-student relationship in a classroom. If the tower is the teacher, and there's several students in the classroom, would be the mobile phones, when my phone wants to make a call, the student is going to raise -- or ask a question, he's going to raise his hand, and when the teacher is ready, the teacher will call on the student. My phone will ask for services saying it needs to make a call, send a text. The tower will then grant services to that mobile, and that's when a record is generated, once those services are granted.

CHAD FITZGERALD: So like I said earlier, there's equipment attached to those antenna at the top of the tower. There's equipment at the base of the tower typically, and that is connected to switches. The switch will then connect out to the rest of the network and ultimately to the rest of the world when I dial a number, or on the reverse, when a number is coming in -- a call is coming in.

CHAD FITZGERALD: Yes. So for every user on their network, they maintain a record. They have to for the nature of their business. Like I mentioned earlier, they have to know generally where you are to deliver a call to you, and they have to know what piece of equipment you're communicating through so that they cannot only allow you to deliver -- you know, make a call, but also once you're in that call, they need to know generally where you are so they can keep your call connected as you're moving around, you know, the city, the United States. They have to hand off from tower to tower, sector to sector. They also -- what's most important to them, they need to know how much you're utilizing their services so they can bill you appropriately each month.

CHAD FITZGERALD: They're designed -- so every cell provider only has a -- set bands that it can operate in. So the FCC, so the federal government, you know, restricts them to a certain area that they can operate in. They have to be able to -- that's a very specified area, so they have to make use of that as efficiently as possible so that they can provide service to more people. So a lot of times -- very common, you'll see that in very densely populated areas, like the city of Boston, they'll put towers very close to each other so that they can handle more subscribers on each tower. They will also further divide those towers up into sectors. So just think of if, you know, we ordered a pizza -- there were three of us that ordered a pizza and we wanted to cut it into three equal shares, or if we had a pie or a cake and we wanted to have three equal shares, that's the same thing they're doing with these towers. They'll sectorize it so they can support more subscribers. I think that answers your question.

CHAD FITZGERALD: Right. So if you -- the most common would be three sectors. And if you think of a 360-degree circle divided by three, in theory you would have a 120-degree sector, you know, on paper.

CHAD FITZGERALD: So like I was mentioning earlier, every phone is programmed to speak a certain language, so -- and the towers have different companies mounted on them. So a lot of people, when they see a tower across the street and they're wondering why they're not getting service, it doesn't -- if I'm carrying a Verizon phone and if Verizon doesn't have, you know, any antenna on that tower that I see, it doesn't exist in my phone's world. So just because you see a tower doesn't mean that's the one your phone is communicating with. And I just put together a slide to show that just because you don't see a tower doesn't mean that there isn't one nearby. So they do try to disguise them occasionally depending on the local ordinances or, you know, depending on where they're trying to place their antenna. So there could be one behind you, you know, instead of one that you're communicating with in front of you. So they're all over the place. So just because you do or don't see one doesn't mean that your phone isn't communicating to the one you're looking at or not.

CHAD FITZGERALD: Yes.

CHAD FITZGERALD: Yes. So every provider maintains a listing of where all their towers are located. Like I mentioned earlier, they have to put towers -- they have to put them out to provide service. So if the AT&Ts of the world could go to downtown Boston, on the tallest building just put one antenna up, they'd be more than happy to do that to maintain maintenance, you know, just make it simple. And if they could provide service to everyone, that would make it simple. But they obviously, like I spoke to earlier, have to put multiple towers, thousands, hundreds of thousands across the United States, out in the United States, and they maintain a list of where all those towers are located. And that list has a unique number identifying every tower within their system and sector. So if you think of it like a fingerprint, there's only one with that unique set of numbers. And it provides a location of where the tower is, the direction from the tower that that sector's providing service to, and a couple of other pieces of information. So in this sample, this is -- I just took a tower listing for the Boston area; I plotted it on a map to show with the blue dots that are in the presentation -- in this page where the towers are for this particular area. And as I mentioned earlier, those towers are then further divided out by sector. So if I'd look at this one in the middle, you can see I drew three 120-degree sectors, and I included the numbers for -- that make that tower and sector unique. So if I was in this area and I wanted to make a call, my phone would communicate with the strongest, clearest signal, which would be this 40361. A record would be generated when I made that call that I started my call on that tower and sector. So we know the general area that that tower is providing service to. And once my phone is connected, it's nothing more than a beacon reporting the signal quality back to the switch or the network. And as I -- if I were to move around this tower, as I got closer to a sector boundary, the signal levels, the quality of signal would degrade on one and increase on this neighboring sector. And when I get to -- they're going to have some built-in overlaps. They can hand my call off from sector to sector. If there was no overlap, your call would just be dropped. And as I get close to that sector, at some point the network is going to -- the switch will hand off that call to the next -- the better signal quality. And if I were just to continue around clockwise, my phone call would just be handed off from sector to sector. And if I were to get on the highway and travel west, I would just be handed off, you know, from sector to sector, tower to tower, and I could -- in theory, if everything is designed out appropriately, I could get on a highway in this area and drive -- and start a call, drive for however long I want to, and I would never know that my call is being handed off from sector to sector, tower to tower; my call would just maintain connectivity to the person on the other end of the line.

CHAD FITZGERALD: Everybody's experienced dropped calls.

CHAD FITZGERALD: Yes, we can pare it down to the Boston area.

CHAD FITZGERALD: Yes, it's very -- if it was printed out it would be inches thick.

CHAD FITZGERALD: Yes. So like I said, we know not only where the tower structure is, but within that tower list we can then determine what direction that sector is providing service to. So if you think of it -- if there was a man standing at the top of that tower and he's got a big floodlight, we can tell which direction that floodlight is pointing down towards the earth. So if it was, you know, zero degree azimuth, that floodlight would be pointing due north, you know, out from that tower structure, providing light or service out to that -- in that direction.

CHAD FITZGERALD: Yes.

CHAD FITZGERALD: So it's kind of hard to see on the screen, but this is -- like I mentioned earlier, every provider keeps a record of use that a subscriber is using on their network. So it's in the form of a call detail record, or a CDR. So a lot of them, from carrier to carrier, contain the same types of information. They might name it a little bit differently. So starting left to right, a lot of the information is fairly self-explanatory. So in the first two columns you have date and time; you have length of time that it took to set up the call; you have an originating and terminating number, so that's just the from-to call. So who the call came from and who the call is going to. So if it's an incoming call to me, the "from" will be the caller ID that will display on my phone, the "to" column would be my phone number. If I was placing a call out, my number would be in the "from," the person I was dialing would be in the "to" column. So just a from-to, nothing more.

CHAD FITZGERALD: Correct.

CHAD FITZGERALD: Then the next column we have the elapsed time that the call took, the amount of time in seconds and minutes that the call took; we have the number that was dialed, very similar to the -- you know, who I'm trying to connect to, the "to" column. The next two columns are just equipment identifiers, so one is the IMEI, which is the serial number of the phone. So it's the serial number burned into the phone equipment. The next one is an MZ, which is the SIM card that you place into the phone. So the MZ is what's tied to your account, what authenticates you and gives you service. Finally, the next two columns, the second-to-last one is going to be the direction. So that tells us if it's an incoming or outgoing call, and the last column is what gives us that location information. So there would be information in there that has the first little section on this left-hand side is that unique fingerprint, that number -- that unique number identifier. It's a combination of numbers that is unique anywhere in that AT&T network. So if I took one of these number combinations and went to the entire United States for the AT&T network, which would be hundreds of thousands of towers and sectors, there's only going to be one entry for that number combination. And then they actually provide a longitude/latitude and the azimuth for that tower, if available.

CHAD FITZGERALD: When the call comes in to the switch, so there will be a record -- that's when the record gets started. When the tower information is populated, that initial tower is the tower that I'm initially granted services on. So the teacher called on me, allowed me to ask my question and granted me resources. So it said: Go make your call on this channel; go make your call or your text, or send me your text. And so when that initially occurs, that's when that initial cell tower is recorded. On some carriers, we can get a terminating tower where the call ended. And with AT&T, every now and again you may get some intermediate handoff tower, but it's not very often in the grand scheme of things.

CHAD FITZGERALD: Right. So with some of the providers, we can get a tower used for a text message. On other providers, because of the way it's routed, we will see that the text occurred but we won't get the actual tower information. And then on some providers, they don't provide us that information at all. And then likewise with some providers, we get data connections. You know, when the person is checking their Facebook or surfing the Internet, we will get some of those too.

CHAD FITZGERALD: Right.

CHAD FITZGERALD: Typically not. If you're using some type of app on your phone, like a Skype, that would recorded as a data connection. But if you're strictly connecting your phone up to Wi-Fi and -- like some of the networks, like T-Mobile will allow you to make texting -- or do texting and make calls over that connection, that would generally not touch the network where we get the CDR from.

CHAD FITZGERALD: Yes.

CHAD FITZGERALD: Yes. I think at the time, in April, it was -- the service had been terminated for lack of payment, as I remember.

CHAD FITZGERALD: That's correct, yes.

CHAD FITZGERALD: I did, yes.

CHAD FITZGERALD: I did.

CHAD FITZGERALD: I did, yes.

CHAD FITZGERALD: So this is just T-Mobile's version of the call detail records, just giving an explanation of each of their columns. Like I said, a lot of the columns all have the same information. In this case T-Mobile gives us a little bit more information for everything. And it's obviously very difficult to read on this screen, but on the far left I had to break it up into two different lines because it's -- the spreadsheet is so long, but starting on the far left on the upper side is the number that was --

CHAD FITZGERALD: So on the far left we have the number that was requested, the target phone number that was requested that the records pertain to; then you have some equipment identifiers, same thing, the IMEI, the electronic serial number of the phone, as well as the MZ or the SIM card that you put in the phone; you have the type of connection, whether it's voice, SMS, a text; you have the date and time for the call; direction of the call, just incoming and outgoing; you just have the other phone number that the phone -- that the call was connected to, so whatever the other party's number was. Then you have a couple pieces of information about the status of the call, whether it was roaming or not. And then kind of over here on the top half of the far right --

CHAD FITZGERALD: There. Now I can. -- you have the -- once again, those unique identifiers in their system, that unique number combination, that is like the fingerprint within the T-Mobile network for what tower and sector was used. And they also provide a location, latitude/longitude. And then continuing on down to the second row, you have the last tower and latitude/longitude that was used when the call terminated. And then you have the market the tower is located in, the switch that was handling the call. And then you have over here just different versions of the duration or the amount of data that was used to send the text message. So you have minutes, seconds of duration, and the data -- the amount of bytes.

CHAD FITZGERALD: Like I mentioned earlier, they all have generally the same information. They might word it a little bit differently, but a lot of the columns are the same. They're not identical to each other, by no means, but a lot of the information is very similar.

CHAD FITZGERALD: I did, yes.

CHAD FITZGERALD: I did. Yes, it is.

CHAD FITZGERALD: I don't think I look -- I think I only did the week around the marathon bombing on this particular target number.

CHAD FITZGERALD: So this is just taking all that information, the call detail records, the tower list or the base station list, and marrying those two pieces of information up in relation to a particular set of calls, and then displaying it graphically on a map so it's more visual versus just lines on a piece of -- you know, just numbers on a piece of paper. So we have the telephone number that you mentioned earlier, the 4634 number, the Tamerlan number. I have a call that was at 1449 and 8 seconds utilizing a tower and sector. The tower is located right here, and the sector that was utilized points off in this direction providing service, you know, to that general area. The kind of shaded area that I have on the map is not to infer that that's the coverage. That's just to give emphasis which direction that sector is pointing and providing service to. And then I had another phone number, another T-Mobile number that ends in 9151 that we analyzed, also a T-Mobile number, and it also made a call at 1449, I think, and 6, I think -- it's hard to see on this screen -- seconds utilizing the same tower but a different sector that points off into the opposite direction of the call. And these two phones were calling each other at that time during the call. The 915 number actually dialed the Tamerlan number. I was also provided addresses of the Forum restaurant and Marathon Sports which I depicted on the map with red markers.

CHAD FITZGERALD: Yes.

CHAD FITZGERALD: Yes, we eventually associated it with him.

CHAD FITZGERALD: I don't remember the exact date, but I remember it was very close to April 15th. That sounds right.

CHAD FITZGERALD: Yes. So you can see it's first name, Jahar; it gives -- it's a prepaid phone so they can put whatever they want on it; last name is T-S-A-R-N-I. And it also shows the date that it was activated, which was, like you said, April 14, 2013.

CHAD FITZGERALD: Yes.

CHAD FITZGERALD: I did.

CHAD FITZGERALD: April 19th or 18th, somewhere in that -- one of those two days.

CHAD FITZGERALD: Yes, I believe it was the first call of the day.

CHAD FITZGERALD: They're both in the same general geographic area hitting that one tower, but further they're hitting different sectors pointing in opposite directions of each other. So I believe the user of one phone is on one side of the tower and the user of the other phone is on the other side of the tower.

CHAD FITZGERALD: No, absolutely not. I can't tell what street they're on, what side of the street. I can't tell that. I can just tell the general geographic area that that phone is located in. And as you can see on this map, I have other red dots of other T-Mobile towers all in the downtown area near this site that we're displaying that was used.

CHAD FITZGERALD: It was pointing -- yes, it was utilizing services off of a sector that definitely points towards the finish line more than the other phone.

CHAD FITZGERALD: That's correct, yes.

CHAD FITZGERALD: So this is just continuing chronologically. We have the 9151 phone receiving a call at 1451, so 2:51 p.m., on the 15th, and it's utilizing that tower and sector pointing in the same direction that it was on the previous slide. And then the other phone, the Tamerlan phone, was actually placing a call to that Jahar phone at the same time, just seconds before, and utilizing the same tower structure but a sector that points more towards the north. So the service area would be up in this direction versus the service area for this other tower and sector being out to the west. And then I've also left on the map those same two reference points of the Marathon Sports and the Forum restaurant. Once again, they're calling each other.

CHAD FITZGERALD: No, we do not get that type of data with these providers.

CHAD FITZGERALD: Well, it's utilizing a sector that's pointing more towards the north. I can't tell if it was actually moving from one sector to the other or if it was just in that overlap area. Like I mentioned earlier, there is a mutual boundary for those two sectors and they could be right in that overlap area where the signal quality is just as strong for both sectors. So it's going to be one or the other.

CHAD FITZGERALD: Right. It's still in the same general area. The service is in the same general area.

CHAD FITZGERALD: Right. Yes.

CHAD FITZGERALD: So this is showing -- and I can't -- if you could zoom in on the one. So this is both phones utilizing the same tower. So the tower's located here, the sector points to the north. And also, just kind of going chronologically a couple of minutes later, at 2:53 p.m. -- and if you zoom back out -- so they're both in -- I guess slightly to the north and east of the two locations, the Marathon Sports and the Forum restaurant a couple of minutes later.

CHAD FITZGERALD: That's correct, yes.

CHAD FITZGERALD: Right. I can't say that they're standing right next to each other or, you know, a block away from each other, but they're utilizing -- they're in the same coverage area, that same tower and sector.

CHAD FITZGERALD: Right. And it's the 9151 number, the Jahar phone, calling the Tamerlan phone.

CHAD FITZGERALD: So at 3:14, and then I think it's 3:38 -- 3:36 two calls from the -- on the Tamerlan phone utilizing two different towers and sectors, one just to the north of the other one. And I also depicted on the map a Whole Foods which came into play when we were conducting the investigation.

CHAD FITZGERALD: Yes.

CHAD FITZGERALD: It is, yes.

CHAD FITZGERALD: This is the Tamerlan number, has a call that was at 3:14 p.m. on April 15th. So just kind of continuing on chronologically.

CHAD FITZGERALD: Yes, at 3:30 p.m. So the next call that was recorded -- or the next phone activity that was recorded was at 3:30 and 32 seconds.

CHAD FITZGERALD: Right. So the coverage area will be generally in that fashion. Same with down here, it would be -- that's the general service area for that phone -- for that sector.

CHAD FITZGERALD: Yes. So when I was here at the time the investigation was occurring, we had received information, I believe, from a witness that the people involved stopped at a Whole Foods.

CHAD FITZGERALD: I used that information. Looking at the phones, once we identified the phone numbers, I told the investigative team that they probably want to go to the Whole Foods and look at the video in between these two times, so between the 3:15 and 3:30 time period, review the video to see if that statement is true, that they might have been caught on video. And I was told the next day that when they --

CHAD FITZGERALD: When they returned, they were able to locate video stills of the two suspects, or at least one of the suspects at the Whole Foods in that time period that I provided to them.

CHAD FITZGERALD: So this is just continuing on with the Tamerlan phone, just showing the tower and sector utilized from roughly 8:30 to 8:47. And then I have another tower and sector depicted on the map that shows kind of further into the night. I believe it was a little after ten o'clock. And I also referenced the address of 410 Norfolk Street, showing where it is in relation to that 1028 call.

CHAD FITZGERALD: Yes.

CHAD FITZGERALD: Yes.

CHAD FITZGERALD: Yes. So I was asked to look at the numbers just kind of as they -- where they were generally being used on April 16th. And if you zoom to the top half, please. So this is just showing on the 16th both the Tamerlan phone and the 5112 phone during -- from 3:30 the 5112 phone is located in the Boston area. The Tamerlan phone is also in the -- utilizing towers in the Boston area at 5:23 -- around 5:23. And then if you zoom to the other towers kind of down at the bottom, it shows that later in the day the 5112 phone traveled down to and utilized towers around 9:47 and 10:25 in the New Bedford/Dartmouth area.

CHAD FITZGERALD: That's correct, yes.

CHAD FITZGERALD: I am, yes.

CHAD FITZGERALD: As I remember, it was very close.

CHAD FITZGERALD: Kind of more of the same, just showing where the phones are -- the towers that the phones are utilizing on the 17th. So once again, if you wouldn't mind zooming in to the top half. It's just showing the Tamerlan phone on the 17th as utilizing towers all in the Boston area starting at 12:29 p.m. and going all the way through 9:46 p.m. And if you could zoom to the bottom.

CHAD FITZGERALD: That's correct.

CHAD FITZGERALD: It's the records for the 5112 number, show the phone utilizing towers once again in the New Bedford/Dartmouth area in the eight o'clock hour, so 8:08 through 8:48 -- and 8:48.

CHAD FITZGERALD: No, I plotted the activity that was available.

CHAD FITZGERALD: It is.

CHAD FITZGERALD: So it's showing both the 9151 phone, the Jahar phone, utilizing a tower kind of over in this side of the map and a sector pointing to the south at 8:17. And I also depicted the two towers and sectors -- or three, actually, that were being utilized by the Tamerlan phone starting at 5:34 and ending at 7:30 p.m. So there's this tower and then two sectors pointing in that direction. And I also put where -- I kept on the map 410 Norfolk Street.

CHAD FITZGERALD: I can't say it was back in. It started being used on the 18th again in the Cambridge area.

CHAD FITZGERALD: Right. So the slides I spoke to earlier showing that phone activity, that was it on the 15th, and then it doesn't get used again until the 18th.

CHAD FITZGERALD: Right. So there's a text, but like I mentioned earlier, we don't get data -- or tower information on texts for T-Mobile. And I'd also like to note also that with T-Mobile, texting is in Pacific time. So to add further confusion to the whole thing, instead of 9:06 a.m. Eastern time, that text actually occurred at a little after noon. So you have to add three hours for texts in T-Mobile.

CHAD FITZGERALD: That's typically a network message of some sort, like maybe something about their bill or voicemail or something to that effect, some kind of text network-generated, is typically what I see.

CHAD FITZGERALD: So this is just showing the night of the 18th. There's a call between the two phones, the Tamerlan phone as well as the 9151 phone a little after 11 p.m., and utilizing two different towers and sectors, which I've depicted on the map, so you have, you know, the general coverage area for the one and then general coverage area for the other, and just showing they're calling each other. The Tamerlan phone is calling the Jahar phone, and just showing the general area of where that service is being provided.

CHAD FITZGERALD: Correct.

CHAD FITZGERALD: Yes.

CHAD FITZGERALD: The towers are located there. It doesn't mean -- obviously, you don't plug into the base of the tower. So the service is provided in the directions that I've depicted on the map. So they could definitely be -- the furthest south tower I'm sure has service on both sides of that river.

CHAD FITZGERALD: No. There could be something physically blocking it. Like if I'm off standing on the other side of the mountain and the tower is physically closer to me but it's getting blocked from that topology, the actual earth, my phone won't be able to see it. So there are situations where the towers get blocked either by, you know, solid structures, the mountains, hills. But obviously the network engineers know the area and they place the towers to provide service in the most appropriate area, immediately around that tower and sector.

CHAD FITZGERALD: Being from Atlanta I have no idea, but I'll take your word for it.

CHAD FITZGERALD: It is. And I've also depicted on the map the address of 45 Laurel Street and where it is in relation to that last call between them.

CHAD FITZGERALD: Correct. The phone records as well as the tower lists.

CHAD FITZGERALD: Yes.

CHAD FITZGERALD: This is a slide I was asked to put together just showing the activity on December 25th and December 26th to just show the area that was being used for the AT&T phone, the 5112 -- the Jahar -- I'm sorry. I don't know which name you said -- what you're calling that phone, but the AT&T 5112 number.

CHAD FITZGERALD: Sorry.

CHAD FITZGERALD: Yes. So I just -- I took that entire day's worth of activity and just kind of put it all on one map showing all the different towers and sectors to show where that phone, you know, was -- the towers and sectors that phone was utilizing for that two-day period, and I also depicted the 410 Norfolk Street address.

CHAD FITZGERALD: Yes.

CHAD FITZGERALD: So there were several text messages -- mostly text messaging, if not all -- utilizing, what -- one, two, three, four -- five different sectors in the Cambridge area over that time period.

CHAD FITZGERALD: Yes.

CHAD FITZGERALD: Right. It might be at the same location. I don't recall. Like I say, sometimes they co-locate on the same structure, the same building, and sometimes they are just nearby each other. I can't remember if exactly -- if this was in the same exact location, but it's definitely near that.

CHAD FITZGERALD: Right. I believe that -- I think this one over here might be 12 -- yeah, 12:31. So, yeah, through 12:35, noon. And it starts as early as a little after -- well, there's actually -- on 12:26 there's another one up here, 5:55. So all the way through 5:55. And then it starts as early as -- let's see, a little after noon on Christmas Day.

CHAD FITZGERALD: I mean, my kids were on break those same two days. I mean, as far as the university, I assume that they're also on break Christmastime. But, yes, the phone was being utilized in Cambridge, and it definitely could have been 410 Norfolk Street. In that area for sure. That tower and sector to the north is providing service to that address.

CHAD FITZGERALD: Hi.

CHAD FITZGERALD: No. It's all just done on the computer utilizing the records and the tower list and the mapping and so forth.

CHAD FITZGERALD: They're just derivative of the original spreadsheet. So they might be pared down to, like in this case, the April 15th through the 18th, but there's no -- I don't create an original spreadsheet, no.

CHAD FITZGERALD: The call detail record?

CHAD FITZGERALD: I utilize the records, the original call detail records, and then I can filter it out -- or filter it down to the calls I'm interested in versus having the thousands of calls.

CHAD FITZGERALD: No. I mean, I've emailed back and forth like the drafts and stuff like that for peer review or to the prosecutors.

CHAD FITZGERALD: The presentation.

CHAD FITZGERALD: I only sent one draft up to Al. I mean, that's the draft. I mean, that was the draft, and that draft becomes a final.

CHAD FITZGERALD: Right. To the person who is doing the peer review, asking them to do the peer review, as well as to Al, showing him that the draft was done and to contact me after he reviewed it.

CHAD FITZGERALD: No, it was all logistics.