Johnny Joe Avalos was born on December 1, 1986, in San Antonio, Texas. He grew up in the South Side of San Antonio, where he spent most of his life. Johnny was intellectually disabled and faced many challenges growing up. Despite these challenges, he was known to be active in his community.

As he got older, Johnny never married and had multiple run-ins with the law. He was arrested several times for making threats, causing damage, and drug possession. These early encounters with the law marked the beginning of a troubled path.

Johnny worked as a dishwasher at a restaurant near downtown San Antonio. After finishing his shifts, he often stalked women, mainly targeting sex workers.

Johnny Avalos, also known as "The San Antonio Strangler," committed a series of murders between 2012 and 2015. His first known victim was Vanessa Lopez, whose body was discovered in October 2012. He continued his killing spree, targeting young women, including 15-year-old Natalie Chavez in 2014 and Rosemary Perez in January 2015. His violent acts typically involved strangling his victims.

Avalos's reign of terror ended when he was arrested in April 2015, initially for a sexual assault linked to one of the murders. Further investigations connected him to multiple killings. He confessed to his crimes and was charged with several counts of murder. In 2019, Avalos pleaded guilty and was sentenced to two life terms without the possibility of parole. He is currently imprisoned at the Preston E. Smith Unit in Lamesa, Texas.