A senator known for advocating on behalf of the victims of crime backed off slightly on comments that suggested serial murderers should be given a rope to hang themselves in prison.

Sen. Pierre Hugues-Boisvenu made the remarks ahead of the Conservative caucus meeting in Ottawa on Wednesday.

"Basically, every murderer should have the right to a rope in his cell," Boisvenu said in French, suggesting the prisoner could then decide whether to take his own life.

After an outcry from the opposition, Boisvenu withdrew the remarks, saying it was inappropriate.

However, even later in the day, he said his original statement should only apply to only "three or four guys."

Boisvenu founded the Murdered or Missing Persons' Families' Association after his daughter Julie was kidnapped, raped and murdered in June 2002.

The Conservative senator said that while he is not generally in favour of the death penalty, it should be considered in cases where there is no hope of rehabilitating the convicted.

Opting for capital punishment over incarceration, he said, referring to an estimated $10-million bill for imprisoning the three recently convicted in the Shafia family murder trial, could save taxpayers a lot of money.

"Not capital punishment, but I think sending them back to their country would be a worse sentence than keeping them in our prisons, where the comfort is much better than over there," Boisvenu said.

During question period Wednesday, NDP interim leader Nycole Turmel suggested the comments reflect the Conservatives' desire to reopen the death penalty debate.

"What Senator Boisvenu (said) is against the law. You can't call on people to kill themselves. The death penalty debate has been closed for decades, why are the Conservatives reopening old debates," Turmel charged, banging her hand on her desk for emphasis.

Prime Minister Stephen Harper responded that the NDP should be more focused on helping the government's justice legislation.

"The senator has clearly withdrawn those words. I think we all understand Senator Boisvenu and his family have suffered horribly in the past. This government is focused on making sure we protect victims in the future," Harper said.

Interim Liberal leader Bob Rae said Boisvenu -- who often speaks on justice issues for the Conservatives -- should no longer be considered an official spokesperson for the government's tough-on-crime agenda.

"I don't see how anybody can be a spokesman for the Conservative party in the Senate on justice issues when you've made a statement like that. It's just completely out of line," Rae said.

Boisvenu was appointed to the Senate by Harper in January 2010.

After a career in the Quebec civil service, Boisvenu rose to public prominence as an advocate for victims of crime. He is also the co-founder of the Le Nid centre for abused women in Val d'Or, and of a school camp for underprivileged youth in Quebec's Eastern Townships.

Harper said last year that despite his personal belief the death penalty sometimes fits the crime, he had no intention of bringing it back into force.