He portrays a deeply troubled man able to communicate only through a beaver puppet in the film directed by Jodie Foster.
Although Gibson’s prominence as an actor has diminished, he has remained a Hollywood fixture and drawn audiences as a director.
Grigorieva, 40, has a teenage son with actor Timothy Dalton.
Gibson was accused of striking her on Jan. 6, 2010, although she did not report it until months later.
The Sheriff’s Department opened its investigation in July, and later began its probe into the extortion allegation made by Gibson.
By then, the pair had broken up and reached a confidential custody agreement regarding their daughter Lucia. Although the exact details are not public, Gibson’s attorney said last year the actor was paying for a house and car for Grigorieva along with child care.
The former couple has appeared opposite each other several times in a family law court that has heard issues related to child care, financial issues and evidence in the criminal investigations of both parents.
Grigorieva’s attorneys lauded the decision to not charge her with extortion, saying the conclusion was reached “after very careful consideration of all the facts and with complete fairness to all involved.”
Grigorieva never invoked her Fifth Amendment rights during interviews and turned over numerous confidential documents, according to a statement issued to The Associated Press by her lawyers Daniel Horowitz, Ronald Litz and Martin Garbus.
“Ms. Grigorieva will now concentrate on co-parenting Lucia, resuming her charitable work for the children of Chernobyl and moving forward with her life,” the statement said, declining further comment.