Case Timeline

From preparations for the April 2013 bombings to the federal prosecution, the 2015 trial and subsequent court rulings.

Events: 28
Span: February 2013–December 2025
Updated: Oct 9, 2026

Preparation

By February 2013Conspiracy
The bombing conspiracy begins
The federal prosecution later established that Dzhokhar and Tamerlan Tsarnaev conspired to use explosive devices, bomb places of public use and destroy property beginning no later than February 2013.
In the archive
- Guilty verdict read in court
Sources
- May 2015 verdict announcement U.S. Attorney's Office, District of Massachusetts
- June 27, 2013 indictment U.S. District Court, District of Massachusetts
About February 6, 2013Preparation
Tamerlan's fireworks purchase
The indictment later identifies Tamerlan's purchase of 48 fireworks mortars in Seabrook, New Hampshire, as an act in furtherance of the conspiracy. The charges describe explosive powder from fireworks as a component of the bombs.
Source
- June 27, 2013 indictment U.S. District Court, District of Massachusetts
About March 20, 2013Preparation
The brothers visit a firing range
According to the indictment, the brothers practiced at a Manchester, New Hampshire, firing range. Dzhokhar rented two handguns and bought ammunition.
Source
- June 27, 2013 indictment U.S. District Court, District of Massachusetts
About April 5, 2013Preparation
Tamerlan orders electronic components
The indictment alleges that Tamerlan ordered electronic components that could be adapted for explosive devices. They were delivered to the brothers' Cambridge residence.
Source
- June 27, 2013 indictment U.S. District Court, District of Massachusetts

Bombings and Manhunt

Apr 15, 2013Bombings
Two bombs explode near the Marathon finish line
The brothers detonate pressure-cooker bombs on Boylston Street. Tamerlan's bomb near Marathon Sports kills Krystle Campbell; Dzhokhar's bomb outside the Forum restaurant kills Lingzi Lu and eight-year-old Martin Richard. Hundreds of people are injured.
Sources
- March 4, 2022 Supreme Court opinion Supreme Court of the United States
- Boston Marathon bombing case history Federal Bureau of Investigation
Apr 18, 2013Investigation
The FBI releases images of two suspects
The FBI publishes photographs and surveillance video and asks the public to help identify the two men. Their names are not yet known to investigators.
Sources
- April 2013 investigation updates Federal Bureau of Investigation
- June 27, 2013 indictment U.S. District Court, District of Massachusetts
Apr 18, 2013Killing
MIT police officer Sean Collier is killed
That night, the brothers shoot and kill Officer Sean Collier in his patrol car on the MIT campus. They try unsuccessfully to take his service pistol.
Sources
- March 4, 2022 Supreme Court opinion Supreme Court of the United States
- Boston Marathon bombing case history Federal Bureau of Investigation
Apr 18, 2013–Apr 19, 2013Carjacking
The brothers carjack Dun Meng; he escapes
The brothers seize Dun Meng's Mercedes SUV and hold him at gunpoint. Meng escapes at a gas station and alerts police, who track the stolen vehicle to Watertown.
Sources
- July 31, 2020 appellate opinion U.S. Court of Appeals for the First Circuit
- Boston Marathon bombing case history Federal Bureau of Investigation
Apr 19, 2013Manhunt
A confrontation with police in Watertown ends in Tamerlan's death
The brothers exchange gunfire with police and use additional explosive devices. Dzhokhar flees in the stolen SUV, running over Tamerlan, who dies from injuries sustained during the confrontation.
Sources
- July 31, 2020 appellate opinion U.S. Court of Appeals for the First Circuit
- Boston Marathon bombing case history Federal Bureau of Investigation
Apr 19, 2013Arrest
Dzhokhar is captured in a Watertown backyard
Police take Dzhokhar into custody after he is discovered hiding in a covered boat. The FBI announces his arrest that evening.
Sources
- April 2013 investigation updates Federal Bureau of Investigation
- Boston Marathon bombing case history Federal Bureau of Investigation

Federal Prosecution

Apr 22, 2013Charges
Federal charges are unsealed; Tsarnaev appears from his hospital room
A criminal complaint charges use of and conspiracy to use a weapon of mass destruction resulting in death, and malicious destruction of property by an explosive resulting in death. Tsarnaev makes his initial court appearance in the hospital.
Source
- April 22, 2013 complaint announcement U.S. Attorney's Office, District of Massachusetts
Jun 27, 2013Indictment
A grand jury returns a 30-count indictment
The indictment covers the Marathon bombings, Collier's killing, the carjacking and the Watertown confrontation. Seventeen counts carry a possible death sentence.
Sources
- June 27, 2013 indictment announcement U.S. Attorney's Office, District of Massachusetts
- June 27, 2013 indictment U.S. District Court, District of Massachusetts
Jul 10, 2013Arraignment
Tsarnaev pleads not guilty to all counts
At arraignment before Magistrate Judge Marianne B. Bowler, Tsarnaev enters not-guilty pleas to the indictment. He is remanded to the custody of the U.S. Marshals Service.
Source
- District court docket U.S. District Court record, via RECAP
Jan 30, 2014Prosecution
The Justice Department authorizes seeking the death penalty
Attorney General Eric Holder announces that the United States will seek a death sentence in Tsarnaev's prosecution.
Source
- January 30, 2014 death-penalty authorization U.S. Department of Justice

Trial and Sentencing

Jan 5, 20152015 TrialTrial
Jury selection begins in Boston
Judge George A. O'Toole Jr. begins jury selection in the District of Massachusetts. Prospective jurors receive instructions about impartiality, publicity and their responsibilities in a capital case.
In the archive
- Browse the 2015 trial
- Jury selection begins
Source
- January 15, 2016 opinion and order U.S. District Court, District of Massachusetts
Mar 4, 20152015 TrialTrial
Opening statements begin the guilt phase
Prosecutors describe Tsarnaev as a willing participant in the attacks. Defense attorney Judy Clarke acknowledges his involvement while arguing that Tamerlan led and influenced him.
In the archive
- Prosecution opening statement
- Defense opening statement
Apr 8, 20152015 TrialVerdict
The jury finds Tsarnaev guilty on all 30 counts
The jury returns guilty verdicts on every count of the indictment. The trial proceeds to a separate penalty phase to determine the punishment for the capital offenses.
In the archive
- Guilty verdict read in court
Source
- May 2015 verdict announcement U.S. Attorney's Office, District of Massachusetts
Apr 21, 20152015 TrialTrial
The penalty phase begins
The same jury begins hearing the penalty case. Jurors must weigh aggravating and mitigating factors in deciding between death and life imprisonment without release on the capital counts.
In the archive
- Penalty-phase jury instructions
May 15, 20152015 TrialPenalty verdict
The jury selects death sentences on six counts
Jurors unanimously select death on six of the 17 capital counts. Those six concern the bomb Dzhokhar placed outside the Forum restaurant, which killed Lingzi Lu and Martin Richard.
In the archive
- Penalty verdict and jury poll
Source
- May 2015 verdict announcement U.S. Attorney's Office, District of Massachusetts
Jun 24, 20152015 TrialSentencing
O'Toole imposes the death sentences and additional prison terms
The court imposes death sentences on Counts 4, 5, 9, 10, 14 and 15, as required by the jury's verdict. It also imposes life sentences and other prison terms on the remaining counts.
In the archive
- Imposition of sentence
Source
- January 15, 2016 opinion and order U.S. District Court, District of Massachusetts

Appeals and Remand

Jan 15, 2016Ruling
The district court denies the post-trial motion
O'Toole denies Tsarnaev's request for a new trial or judgments of acquittal. The motion challenges the trial venue and the legal basis for the firearm convictions, among other issues.
Source
- January 15, 2016 opinion and order U.S. District Court, District of Massachusetts
Jul 31, 2020Appeal
The First Circuit vacates the death sentences and reverses three convictions
The court reverses convictions on Counts 13, 15 and 18 with directions to acquit, and vacates the death sentences on Counts 4, 5, 9, 10 and 14. It orders a new penalty trial while leaving the other convictions and life sentences intact.
Source
- July 31, 2020 appellate opinion U.S. Court of Appeals for the First Circuit
Mar 22, 2021Appeal
The Supreme Court agrees to review the death-sentence ruling
The Supreme Court grants the United States' petition to review the First Circuit's decision. The government's challenge concerns jury selection and the exclusion of evidence about the 2011 Waltham killings.
Sources
- Supreme Court docket, No. 20-443 Supreme Court of the United States
- March 4, 2022 Supreme Court opinion Supreme Court of the United States
Mar 4, 2022Appeal
The Supreme Court reverses the death-sentence vacatur
In a 6–3 decision, the Supreme Court rejects the two grounds for setting aside the death sentences. The separate reversal of convictions on Counts 13, 15 and 18 remains undisturbed; other appellate issues return to the First Circuit.
Sources
- March 4, 2022 Supreme Court opinion Supreme Court of the United States
- March 21, 2024 appellate opinion U.S. Court of Appeals for the First Circuit
Mar 21, 2024Remand
The First Circuit orders an inquiry into potential juror bias
The court directs the district judge to investigate Jurors 138 and 286 and retains jurisdiction over the appeal. A new penalty trial is required if disqualifying bias is established or faded memories prevent a determination. The remand itself does not vacate the death sentences.
Source
- March 21, 2024 appellate opinion U.S. Court of Appeals for the First Circuit
Mar 28, 2025Ruling
O'Toole denies the request for his recusal
Tsarnaev asks O'Toole to withdraw from the juror-bias inquiry and provide disclosures about his public comments. The judge denies the motion. This ruling concerns who will conduct the inquiry, rather than whether the jurors were biased.
Source
- District court docket U.S. District Court record, via RECAP
Jul 31, 2025Appeal
The First Circuit declines to order O'Toole's recusal
The court denies Tsarnaev's petition for a writ of mandamus, finding that he has not met the demanding standard for this remedy. The judgment resolves the recusal request, not the merits of the juror-bias inquiry.
Source
- July 31, 2025 recusal judgment First Circuit court record, via RECAP
Dec 18, 2025Appeal
The First Circuit denies rehearing in the recusal matter
The original panel denies rehearing, and the court denies rehearing en banc. The order leaves the July 2025 denial of the recusal petition in place.
Source
- December 18, 2025 rehearing order First Circuit court record, via RECAP