Dorothea Puente was born in Redlands, California in 1929. She had a difficult childhood, as her parents died when she was just a young girl, and she was separated from her siblings and sent to live in different homes. By 16 years old, Puente had turned to sex work to make ends meet, according to World History. In the late 1940s, Puente started stealing and forging checks, and she spent some time in jail for her crimes.

Puente was headed down a dark path, and forging checks and stealing escalated to murder. By running a boarding house and providing a home for those in need, Puente seemed like she had a heart of gold. However, she had ulterior motives. She killed her borders and cashed in their Social Security checks, and her illicit activities continued until Alvaro Montoya, also known as Bert, went missing in 1988. As reported by the Los Angeles Times, a social worker called Puente to check on Montoya, but the landlady said that Montoya left the boarding house and had gone to Mexico. Puente provided different explanations whenever the social worker called, and this aroused suspicions.