The longtime companion of notorious fugitive James "Whitey" Bulger agreed to plead guilty to several charges against her related to her infamous 16-year run from authorities with her alleged mobster boyfriend.

Catherine Greig will plead guilty to the charges of conspiracy and two counts of identity theft charges, according to court documents.

Greig will not have to testify against Bulger at his upcoming trial, CNN affiliate WCVB reported.

"In early 1995, I agreed to join Bulger and travel with Bulger during his flight from law enforcement. From January 1995 through June 22. 2011, I also agreed with others, including Bulger, to harbor and conceal him from law enforcement," Greig said in court documents.

Bulger, 82, has previously pleaded not guilty to all charges against him, including 19 murder charges.

Bulger, who is being held without bail, was the head of a South Boston Irish gang before he fled an impending racketeering indictment in 1995. He evaded law enforcement for 16 years before he and Greig were arrested in June 2011 in Santa Monica.

The couple had, for several years, hid in plain sight in this palm-tree-lined oceanside city by Los Angeles in a three-story building named Princess Eugenia.