Mary was the first member of the Manson Family. She moved to California and got a job as a librarian at UC Berkeley. She met Charlie while walking her poodle and they soon became close friends. Charlie eventually moved into her apartment and they started sleeping together after several weeks. She later quit her job, packed up and started a journey with Charlie in his Volkswagon Van as they drifted around California together meeting other young women.
In 1967 Mary became pregnent for Charlie and later gave birth to thier son who they named Valentine Michael nicknamed "Pooh Bear" at the spiral staircase house in Topanga Canyon. Charlie delivered Pooh Bear himself and bit the umbillical cord free.
In 1968 Mary witnessed Bobby Beausoleil stab Gary Hinman, she and Susan Atkins took turns smothering Hinman's face as he lay dying. Mary was later implicated in the murder but was granted immunity for states evidence.
Mary became a regular on the corner by the Court House holding daily vigils for Charlie, Susan, Patricia and Leslie.
In 1971 along with five other Family members Mary was involved in an armed robbery which ended up in a shoot out between them and the police. The group had stolen close to 150 guns and planned on hijacking a 747 jet in which they would kill one passenger every hour until Manson and company were released from jail. For this crime she served six years in jail while Pooh Bear went to live with her parents. Mary has since renounced Manson, changed her name and is said to be living in the Midwest.