Sean Vincent Gillis was born on June 24, 1962, in Baton Rouge, Louisiana. He was the son of Yvonne and Norman Gillis. His father left the family shortly after he was born. As a result, Sean was raised by his mother and his grandparents. Growing up in southern Louisiana, he faced challenges without his father.

Gillis began to have trouble with the law when he was 17 years old. His record included minor offenses such as traffic citations and DUI. He also faced charges for possession of marijuana and contempt of court. These early run-ins with the legal system marked the start of a troubled life.

His early years were not extensively documented, but it is noted that he had a difficult childhood. These experiences would shape his life as he grew older. He would later be known for committing serious crimes. However, this part of his life did not disclose much about the reasons behind his actions. His criminal behavior escalated over the years, leading to significant events later in his life. Sean Vincent Gillis committed his first known murder in 1994.

In March 1994, Sean Vincent Gillis committed his first known murder. He killed 82-year-old Ann Bryan at her home in Baton Rouge, Louisiana. He had intended to assault her, but when she screamed, he became frightened. To silence her, he slit her throat and stabbed her multiple times. After the attack, he left her body in her residence.

In May 1999, Gillis began stalking a woman he noticed jogging. After three weeks of following her, he found 52-year-old Hardee Schmidt. On May 30, 1999, he hit her with his car, which caused her to fall into a ditch. He then strangled her with plastic wrap and forced her into his car. After sexually assaulting her, he placed her body in the trunk of his car and discarded it two days later.

Following Schmidt’s murder, Gillis continued to kill. His activities went unnoticed by law enforcement for the next few years. He murdered a total of eight women in the Baton Rouge area between 1994 and 2004.

In February 2004, he killed Donna Bennett Johnston, his final victim. Gillis raped her and strangled her with a nylon tie wrap. He later mutilated her body after her death. Her remains were discovered in a drainage canal near Louisiana State University.

In April 2004, police found tire tracks near Johnston's body. The tracks helped investigators trace them back to Gillis. DNA evidence linked him to other victims, leading to his arrest on April 29, 2004. At different times, he was charged with several murders. In July 2008, he was found guilty of three murders and sentenced to life in prison. He had also admitted to other murders during the investigation.

Sean Vincent Gillis is currently serving his sentence in the Louisiana State Penitentiary.