Should one of the Catholic Church’s most prominent death penalty abolitionists be allowed to testify on behalf of Boston Marathon bomber Dzhokhar Tsarnaev?

Sister Helen Prejean, whose story inspired the 1995 Susan Sarandon film “Dead Man Walking,” is on the defense’s witness list as Tsarnaev’s lawyers try to convince a jury to give their client life in prison rather than the death penalty.

But the government says: No way.

Prosecutors fear jurors from heavily Catholic Greater Boston could be persuaded by the 76-year-old nun’s anti-death penalty message.

Prejean was at the Boston courthouse Thursday, but was not called to testify. Judge George O’Toole Jr. is expected to decide Monday if Prejean, a member of the Congregation of Saint Joseph, will be allowed to take the stand during this penalty phase of the trial.

During the jury selection phase earlier this year, some potential jurors were dismissed because they said their faith prohibited them from voting for the death penalty.

Massachusetts abolished capital punishment in 1984, but terrorism cases are tried in federal court, where the death penalty is still on the books.

Polls show most Bostonians oppose the death penalty for Tsarnaev, and Massachusetts Catholic bishops released a letter last month restating the Church’s opposition.

“The defendant in this case has been neutralized and will never again have the ability to cause harm. Because of this, we, the Catholic Bishops of the Commonwealth of Massachusetts, believe that society can do better than the death penalty.”

A majority of Catholics in the United States — 59 percent of white Catholics in one recent poll — still favor the use of the death penalty, but a joint editorial by conservative and liberal Catholic publications last month argued against it.

Tsarnaev was convicted last month in the 2013 bombing that killed three people and injured more than 260. His lawyers admitted he participated in the bombings, but have argued that his life should be spared because his older brother was the mastermind of the attack and lured Dzhokhar, then 19, into the plot.

Prosecutors have portrayed him as an equal partner with his brother and a heartless terrorist who placed one of the bombs behind a family, killing 8-year-old Martin Richard and maiming his sister Jane, who lost a leg.

Material from the Associated Press was used in this report.