Boston Marathon bomber Dzhokhar Tsarnaev has expressed remorse over the bombings, a defense witness testified as his lawyers finished their case to spare his life.

Forty witnesses testified for Dzhokhar Tsarnaev, including anti-death penalty advocate Sister Helen Prejean.

Helen Prejean testified on May 11 that Dzhokhar Tsarnaev told her of the bombing victims: “No one deserves to suffer like they did.”

The April 2013 bombings killed three people and injured more than 260.

Dzhokhar Tsarnaev, 21, has expressed genuine regret and sorrow over the bombings, the Roman Catholic said.

Prosecutors pushed to exclude her testimony, but a judge decided to allow it.

Helen Prejean began prison ministry in 1981 in New Orleans and corresponded with Patrick Sonnier, a death row inmate who had been convicted of killing two teenagers.

She wrote a best-selling book on her experiences called Dead Man Walking, which was later turned into a movie.

Prosecutors will now call rebuttal witnesses. Both sides will deliver closing arguments before the jury decides Dzhokhar Tsarnaev’s fate.

Dzhokhar Tsarnaev’s lawyers have admitted he played a role in the attacks but said that his older brother, Tamerlan, was the driving force.

The defense emphasized on young age of Dzhokhar Tsarnaev who was 19 at the time of the attacks.

Lawyers also highlighted Dzhokhar Tsarnaev’s rough family life. The Tsarnaevs – ethnic Chechens – had lived in the former Soviet republic of Kyrgyzstan and the volatile Dagestan region of Russia, near Chechnya, before moving to the US in 2002.

Teachers called Dzhokhar Tsarnaev “sweet” and “hardworking” while other witnesses said his mother was obsessed with religion and his father had post-traumatic stress disorder, contributing to his actions.