Boston bomber remorseful, US nun tells trial

A sketch of the scene inside the courthouse during the trial of Dzhokhar Tsarnaev in Boston, Massachusetts, on May 4, 2015. The sketch shows Tsarnaev's cousin Raisat Suleimanova (right) testifying with an interpreter. -- PHOTO: EPA 
A sketch of the scene inside the courthouse during the trial of Dzhokhar Tsarnaev in Boston, Massachusetts, on May 4, 2015. The sketch shows Tsarnaev's cousin Raisat Suleimanova (right) testifying with an interpreter. -- PHOTO: EPA 
Sister Helen Prejean is surrounded by media after testifying at John Joseph Moakley United States Courthouse as the Tsarnaev defence nears its end of presenting case in sentencing phase of the Boston Bomber Trial on May 11, 2015. -- PHOTO: AFP
Sister Helen Prejean is surrounded by media after testifying at John Joseph Moakley United States Courthouse as the Tsarnaev defence nears its end of presenting case in sentencing phase of the Boston Bomber Trial on May 11, 2015. -- PHOTO: AFP

NEW YORK (AFP) - Convicted Boston bomber Dzhokhar Tsarnaev has expressed sincere remorse for carrying out the deadly attacks in 2013, a prominent American nun and anti-death penalty campaigner told his trial on Monday.

Sister Helen Prejean, who was portrayed in an Oscar-winning performance by actress Susan Sarandon in Hollywood movie Dead Man Walking, was the final witness called by the defence in its bid to save Tsarnaev from death.

"He said emphatically, 'no one deserves to suffer like they did,'" the 76-year-old testified at the trial in Boston, according to The New York Times.

Prejean said she had met Tsarnaev in prison five times since March and that she believed he was "absolutely sincere". Tsarnaev's voice had "pain in it" when he recognised the hurt he had caused, she recalled.

"I had every reason to think he was taking it in and he was genuinely sorry for what he did." It was the first mention of the 21-year-old expressing remorse for his actions since his trial began in March.

The only emotion he has displayed was to wipe his eyes as a distraught aunt was removed from the courtroom, too overcome to testify.

Prejean won international recognition as a compassionate Catholic nun who counseled a convicted murderer on death row in the state of Louisiana, which inspired the book and film Dead Man Walking.

The film won Sarandon the Oscar for best actress in 1996 and three Academy Award nominations, including best actor for Sean Penn.

Tsarnaev was convicted last month on all 30 counts related to the bombings, the murder of a police officer, a carjacking and a shootout while he and his older brother Tamerlan were on the run.

The double bombings at the Boston Marathon finish line killed three people and wounded 264 others on April 15, 2013.

The defence and prosecution are to present closing statements Wednesday before a jury deliberates whether he should be sentenced to death or life without parole in America's most maximum security prison.

Tamerlan was killed in a shootout with police, leaving his brother to face punishment alone.