Julio Segundo Pérez Silva was born on July 15, 1963, in Puchuncaví, Valparaíso, Chile. As a child, he was known by the nickname "Segua." He spent most of his early years playing and living among the streets of Puchuncaví. People who knew him during his school days described him as a quiet and introverted student.

At the age of 22, Julio married Monica Cistemas, who was originally from La Calera. This couple had two daughters together. Afterward, he spent five years with Marianela Vergara, who had two daughters from a previous relationship. With Marianela, he returned to Puchuncaví and built a reputation as a good husband.

In the mid-1990s, seeking better job opportunities, Julio moved to Iquique. There, he found work loading sacks of salt. During a party, he met Nancy Boero, who was fourteen years older than him and a mother of six. After just two weeks, they decided to live together and settled in a neighborhood called “La Negra.” Later, they moved to another sector known as “Autoconstruccíon.”

Julio eventually left his job and began working illegally as a taxi driver.

On September 15, 1998, Julio Pérez Silva picked up 17-year-old Graciela Montserrat Saravia in Iquique. He claimed she offered money for sex, but he realized she wanted to steal from him. In anger, he beat her to death and left her body on a beach.

On November 24, 1999, Pérez offered a ride to 13-year-old Macarena Sánchez while driving in Alto Hospicio. After threatening her with a knife, he raped her, tied her hands, and threw her into a deep pit called the Huantajaya Pique.

In February 2000, he attacked Sara Gómez on the 21st and just two days later, he murdered 23-year-old Angelica Lay. Both murders occurred in remote desert areas.

On March 23, he killed 14-year-old Laura Zola in a similar manner, also raping and murdering her in Huantajaya. On April 5, he attacked 16-year-old Katherine Arce, raping and killing her, before burying her body in a dump.

On May 22, he kidnapped 17-year-old Patricia Palma after she left school. He raped and killed her, leaving her body in Huantajaya with those of Sánchez and Zola.

On June 2, he murdered Macarena Montecinos, and the same fate hit 15-year-old Viviana Garay a month later. These crimes drew attention when Viviana's father, Orlando Garay, rallied other families to seek justice, stopping Pérez's killings for a time.

However, on April 17, 2001, Pérez attacked again. He targeted a girl under 16 named Maritza. He threatened her with a knife and raped her, but she escaped and reported his attack to the police.

On October 4, 2001, Pérez assaulted a young woman named Bárbara Nuñez. He struck her with a stone and assumed she was dead, but she survived and reported him. This led to his arrest that same day.

During questioning, Pérez confessed to the murders and rapes, claiming he acted alone. After his arrest, he provided police with details to find the bodies of other victims.

On February 26, 2004, Pérez was sentenced to life imprisonment for the murders of 11 adolescents and 3 adults. He also received additional sentences for two rapes and an attempted murder. He remains incarcerated in a high-security prison in Chile.