SAN QUENTIN (CBSLA) — Lonnie D. Franklin Jr., a convicted serial killer known as the “Grim Sleeper,” died at San Quentin State Prison. He was 67.

Franklin Jr. was found unresponsive in his cell on Saturday night, and was pronounced dead at 7:43 p.m. His cause of death is pending the results of an autopsy. Authorities, however, said there were no signs of trauma.

Franklin Jr. was on death row for the murders of nine women and one teenage girl committed between 1985 and 2007.

He was sentenced to death on Aug. 10, 2016, for 10 counts of first-degree murder and one count of attempted murder.