LAS VEGAS -- The killings of a Las Vegas couple were plotted by their son, who watched as a friend shot and stabbed them in their mobile home, police said Thursday.

Victor Veliz surrendered to detectives after his mother called police and said her son killed Thomas and Carla Lee Chester.

Their son, 18-year-old Timothy, was arrested Thursday morning near the Hoover Dam.

Slideshow: Veliz, Chester Family In Photos

According to a police report, the couple lived in the Heritage Village Mobile Home Park with their son, 18-year-old Timothy, daughter, 22-year-old Amanda, and her two children.

Police first suspected Timothy Chester killed his parents after his sister found the bodies late Wednesday afternoon. But Veliz’s confession stated that Chester approached him about killing the couple and handed him a gun in the family’s home.

Video: Teen Missing After Parents Killed

Veliz then shot the couple, stabbed them and washed his hands clean in the kitchen sink, according to the police report.

Timothy Chester disappeared after the killings. Veliz told police he heard a car horn honking while he was inside the trailer and said Chester left with another gun, a pistol taken from his father’s closet.

Police would not say whether a gun was found when Chester was arrested.

After surrendering, police said Veliz handed over a gun wrapped in his bloody clothing.

Veliz is charged with murder, conspiracy and burglary.