Chad Fitzgerald

Chad Fitzgerald testified for the prosecution on Day 31 as an FBI agent who analyzed cell-site records. He explained how he combined carrier call-detail records with tower listings to map contacts between phones associated with the Tsarnaev brothers around 2:49, 2:51, and 2:53 p.m. on April 15, 2013, and later activity in Boston, Cambridge, and the New Bedford/Dartmouth area. He emphasized that sector use could not establish an exact address, movement, distance from a tower, or proximity between users.

His December 25 and 26, 2012 mapping showed the 5112 phone using Cambridge sectors, but he described use at 410 Norfolk Street as possible rather than established. He also described a Whole Foods surveillance lead and secondhand information that investigators found stills showing two suspects, or at least one suspect. The court allowed that testimony over defense objections and permitted Exhibits 1440 and 1485 to be used as illustrative presentations while deferring admission.

During voir dire about preparation materials, Fitzgerald told Miriam Conrad that he took no notes, wrote no reports or memoranda, and filtered existing spreadsheets rather than creating an original spreadsheet. He said he sent one presentation draft to the prosecutor and characterized peer-review and prosecutor emails as logistical. Conrad requested drafts; Chakravarty said a draft had already been disclosed. No express production ruling followed.

On cross-examination, Fitzgerald agreed that the April 15 records were consistent with Dzhokhar being near the Forum restaurant and Tamerlan near Marathon Sports, but said he did not know whether a person-to-person conversation occurred. T-Mobile listed durations of 19 and 30 seconds for the 2:49 and 2:51 p.m. calls, while a handset extraction Conrad identified as Tamerlan's listed eight and 18 seconds. Fitzgerald could not explain the extraction software's calculations or determine whether those figures were consistent. The court admitted the T-Mobile records as Defense Exhibit No. 2.

On redirect, Fitzgerald distinguished carrier switch records from handset logs and reiterated that recorded duration measured network-resource use. The court sustained several objections to proposed timing, location, movement, and iMessage inferences and declined to admit the reviewed AT&T records; those records and the handset extraction remained identification-only exhibits. On recross, Fitzgerald clarified that wireless calls would appear in data-connection records, which his charts had not used. He was then excused.