Boston Marathon bomber Dzhokhar Tsarnaev’s appellate team presented their oft-delayed opening argument Thursday, urging sparing him a federal execution and allowing him to be retried for the 2013 Patriots Day terror attack that killed an 8-year-old boy and two women.

Their premise is summed up in the opening line: “This case should not have been tried in Boston.

“Forcing this case to trial in a venue still suffering from the bombings was the District Court’s first fundamental error, and it deprived Tsarnaev of an impartial jury and a reliable verdict, in violation of the Fifth, Sixth, and Eighth Amendments,” the brief states.

The partially redacted document filed in the U.S. Court of Appeals for the First Circuit spans 1,124 pages, nearly half of which is the 500-page opening brief alone.

Absent a new trial, Tsarnaev’s team is asking the Appeals Court to reverse his death sentence and order a punishment of life imprisonment.

Tsarnaev, 25, has been in solitary confinement at the federal Supermax prison in Florence, Colo., since his 2015 conviction.

Tsarnaev’s trial attorneys made repeated bids for a change of venue.

His appeal focuses on and echoes several familiar protests raised during his trial, chief among them the argument that he was a pawn of his domineering big brother, Tamerlan Tsarnaev.

Among other things, the public defenders accuse Tsarnaev’s jury forewoman, a restaurant manager his attorneys tried to get removed, of retweeting a social media post calling the University of Massachusetts Dartmouth sophomore a “piece of garbage” before she received a juror summons, but that she claimed during questioning for her suitability to serve she had not “commented on this case.”

A second juror, a male municipal worker, outright “disobeyed the Court’s instructions,” the brief asserts, by joining a Facebook discussion about the case before he was seated.

Attempts to reach both jurors were not immediately successful.

Tsarnaev was a Cambridge resident at the time of the attacks. An admitted self-radicalized terrorist, he cheated death after being shot in the face and extremities by law enforcement during an unprecedented manhunt that virtually shut down the city.

He later told federal investigators he and his late older brother Tamerlan — a suspect in a still-unsolved 2011 triple-homicide in Waltham — were avenging U.S. military actions in the Middle East.

Tsarnaev’s appeal blames his 26-year-old brother for his involvement, calling Tamerlan “a killer, an angry and violent man” who “conceived and led this conspiracy.” And but for his influence, “Jahar would never have been on Boylston Street on Marathon Monday.

“Tsarnaev admitted heinous crimes,” the lawyers acknowledge, “but even so — perhaps especially so — this trial demanded scrupulous adherence to the requirements of the Constitution and federal law. Again and again this trial fell short.”

The Tsarnaevs detonated two homemade pressure-cooker bombs packed with shrapnel near the marathon finish line in Copley Square 12 seconds apart on April 15, 2013.

Three spectators were killed — 8-year-old Martin Richard of Dorchester, Krystle Campbell, 29, a restaurant manager from Medford, and Boston University graduate student Lingzi Lu, 23.

More than 260 other people were injured. Sixteen of them lost limbs in the blasts. Three days later, the brothers shot and killed MIT Police Officer Sean Collier, 27, in his cruiser during an ambush on campus and failed attempt to steal his service weapon.

A federal jury convicted Tsarnaev in April 2015 of 30 charges, including use of a weapon of mass destruction and conspiring to detonate a bomb in a public place, both resulting in death.