Federal prosecutors on Thursday are set to ask a judge to order former Boston mob boss James "Whitey" Bulger's girlfriend to spend three more years in prison for refusing to say if anyone helped the couple during their 16 years on the run.

But lawyers for Catherine Greig, 64, said that punishment was too severe for a woman they described as an animal lover and model prison inmate who was never accused of joining Bulger's murder and mayhem.

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Greig was arrested alongside Bulger in 2011 when federal agents caught up with the pair in a seaside condo in Santa Monica, California, where they were living with a cache of weapons and cash. Bulger fled Boston in 1995 after a tip from a corrupt FBI agent that arrest was imminent.

He was on the FBI's "Ten Most Wanted" list for most of his time on the run, and his story inspired multiple films, including 2015's "Black Mass."

Bulger, now 86, was convicted in 2013 of murdering or ordering the killings of 11 people, following a monthslong racketeering trial that exposed his corrupt relationship with the Boston office of the FBI, which turned a blind eye to Bulger's Irish-American gang as it focused its energy on the Italian-American Mafia. He is currently serving two consecutive life sentences.

Greig was sentenced to eight years in 2012 after pleading guilty to identity fraud and harboring a fugitive. Her sentence on contempt of court charges for refusing to testify would be added onto that time.

"She did not plead guilty to aiding and abetting a man who by the government's account was a mastermind of criminal activity and a killing machine," her attorneys wrote as they recommended a six-month sentence. "For 16 years, she kept him docile, happy and avoiding any violence."

They also noted that Greig's initial sentence was longer than the five years Bulger associate Kevin Weeks served for his role as an accessory to five murders.

Federal prosecutors argued that Greig was inflicting further injury on the survivors of Bulger's victims by refusing to testify.

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The pair have held to the underworld's code of silence in their court appearances. Bulger's attorneys began his trial by calling him an "organized criminal" and spent much of their energy denying prosecutors' claims that he had been an FBI informant.

Bulger claims to have paid agents for tips but provided no information in return.