Joseph James DeAngelo Jr. was born in Bath, New York, on November 8, 1945, to parents Kathleen Louise DeGroat and Joseph James DeAngelo Sr., a sergeant in the United States Army. Growing up as the youngest of four siblings, DeAngelo's childhood was marred by traumatic experiences, including witnessing the assault of his sister Connie while the family was stationed in West Germany.

During his school years in Rancho Cordova, California, DeAngelo showed troubling behavior, including burglaries and animal cruelty. After receiving his GED from Folsom High School in 1964, he joined the United States Navy, serving during the Vietnam War. Post-military, he pursued an education in police science and criminal justice, earning degrees with honors and completing further police training.

DeAngelo's career in law enforcement began in 1973 but ended abruptly in 1979 when he was caught shoplifting and subsequently fired after making threats against his chief of police. His personal life during this period was equally tumultuous. An engagement to Bonnie Jean Colwell ended due to his manipulative behavior, and in 1973, he married Sharon Marie Huddle. The couple had three daughters and led a seemingly normal life in Citrus Heights, although they separated in 1991 and divorced following DeAngelo's arrest in 2018.

Professionally, DeAngelo worked as a truck mechanic from 1990 until his retirement in 2017. Despite his appearance as a family man and a worker, DeAngelo harbored dark secrets. He was linked to numerous offenses committed during his years as a husband and father, which his family claimed to know nothing about. DeAngelo's arrest in 2018 brought an end to decades of mystery surrounding his crimes. He was living with a daughter and granddaughter at the time, maintaining a façade of normalcy while neighbors reported his frequent angry outbursts.

Starting in the 1970s, DeAngelo's criminal activities escalated. He worked as a police officer in Exeter and Auburn but was dismissed after a shoplifting incident in 1979. His personal life was tumultuous, with a broken engagement to Bonnie Jean Colwell due to his manipulative behavior, and a marriage to Sharon Marie Huddle in 1973, which ended in separation in 1991 and eventually divorce after his arrest.

DeAngelo was linked through DNA evidence to multiple murders and over 50 rapes across several California counties, along with countless incidents of theft, burglary, and vandalism. His criminal methods were meticulous and horrifying, often involving extensive surveillance of neighborhoods and brutal attacks on victims in their homes.

Known as the East Area Rapist, his crimes began with burglaries and escalated to brutal attacks and murders, profoundly affecting communities and evading capture for decades. DeAngelo's ability to evade capture allowed him to continue his crimes until his arrest in 2018, following advancements in DNA technology and genealogy tracing.

In 2018, DeAngelo was charged with numerous counts of murder and kidnapping. In 2020, he pleaded guilty to avoid the death penalty and received multiple life sentences, finally ending the long and painful chapter he inflicted on so many.