CHESTER, Calif. -- A 20-year-old man who crashed his truck into a stand of pine trees as he headed home after learning his sister had been killed has died, hospital officials said.

Billy Carrigan died Tuesday at Enloe Medical Center in Chico, said Christina Chavira, a hospital spokeswoman. He had been in critical condition at the hospital since Sunday, when he got into the accident along Highway 36 outside his hometown of Chester, about 150 miles north of Sacramento.

Carrigan's sister, Jennifer, and her friend, Steven Furtado, had been found dead Sunday afternoon inside the family's home. Jennifer Carrigan's mother found the pair in her daughter's bedroom.

Early reports said the couple, both 18, had gone to prom the night earlier but Sgt. Greg Hagwood said there was no indication they went to the high school dance.

Jennifer Carrigan's ex-boyfriend, 18-year-old Reyes Carrillo, was arrested in connection with the deaths. Investigators believe Carrillo acted alone and that Carrigan and Furtado were stabbed multiple times late Saturday or early Sunday, said Plumas County Sheriff's Patrol Commander Gerry Hendrick. Autopsies were being conducted to determine the exact cause and time of death.

Carrillo did not enter a plea in court Tuesday and his arraignment was postponed, said Hendrick, who attended the court hearing.

Hagwood said Jennifer Carrigan and Carrillo had dated for several years and broke up within the last couple of months.

Billy Carrigan was a student at the Berkeley City College, said friend Sarah Rubin. The car accident occurred when he lost control of his pickup truck while driving around a sharp curve on his way home.

"It's really affected people down here strongly," Rubin said. "He wanted to start studying Mandarin Chinese and he wanted to visit the East Coast. He was so enthusiastic and uplifting and put a smile on everyone's face."

A memorial fund has been set up by the Seneca Health Care District to help Joane Carrigan pay for her children's funeral expenses.