Patricia Krenwinkel was born on December 3, 1947, in Los Angeles, California. She was the daughter of an insurance salesman and a homemaker. Growing up, Patricia faced challenges at school. She attended University High School and later Westchester High School in Los Angeles. During her time in school, she was often bullied by other students. She struggled with low self-esteem and was teased for being overweight as well as for excessive body hair, a condition caused by an endocrine issue.

When Patricia was 17, her parents divorced. She chose to stay in Los Angeles with her father after the separation. After graduating from Westchester High School, she taught catechism, which is a form of religious instruction in the Roman Catholic faith. At one point, she considered becoming a nun. Patricia enrolled in Spring Hill College, a Jesuit college in Mobile, Alabama. However, she dropped out after just one semester. She then moved back to California and started living with her half-sister in Manhattan Beach. There, she found a job as a processing clerk in an office.

In 1967, Patricia met Charles Manson in Manhattan Beach. Along with two other women, she was drawn to Manson's charisma and the attention he gave her.
 

On August 9, 1969, Patricia Krenwinkel took part in the murders at 10050 Cielo Drive. This was the home of actress Sharon Tate and four others. Krenwinkel stabbed Abigail Folger during this incident and later called on Tex Watson to join in. During her trial, she stated, "I stabbed her and I kept stabbing her." When asked about her feelings during the act, she said it felt like "nothing."

The following night, on August 10, 1969, Krenwinkel participated in more murders at the LaBianca home. Along with Charles Manson, Watson, Leslie Van Houten, and others, she was involved in the killings of Leno and Rosemary LaBianca. Afterward, Krenwinkel claimed her only thought was that "Now he won't be sending any of his children off to war." Following the murders, the group stayed in the LaBianca home, eating food and showering before leaving.

Krenwinkel was arrested on December 1, 1969, near her aunt's home in Mobile, Alabama. This arrest came after her fellow Manson follower Susan Atkins shared details of their involvement in the murders with other inmates. Krenwinkel was indicted for seven counts of first-degree murder and one count of conspiracy to commit murder.

During her trial, which began in 1970, Krenwinkel's lawyer suggested that her fingerprints at the crime scene might mean she was simply a guest. Throughout the trial, Krenwinkel showed support for Manson and the group, even participating in acts such as shaving her head and carving an "X" on her forehead. She was found guilty and sentenced to death on March 29, 1971.

Krenwinkel spent time on death row before her sentence was commuted to life in prison following a California Supreme Court ruling in 1972. Over the years, she took part in many prison programs and maintained a clean record. She earned a degree in Human Services and taught reading to other inmates.

Krenwinkel's first parole hearing occurred in 1978. She expressed remorse for her actions, particularly regarding Abigail Folger. Despite multiple parole hearings, including one in 2016 where her defense claimed she suffered from battered woman syndrome, Krenwinkel was denied parole repeatedly. In 2022, she was granted parole, but Governor Gavin Newsom later reversed the decision, citing a continued risk to public safety. As of now, Krenwinkel remains incarcerated at the California Institution for Women in Chino, California.