U.S. 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.

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.