Lonnie David Franklin Jr., the so-called Grim Sleeper serial killer who preyed on Los Angeles women for more than two decades, died Saturday while on death row at San Quentin prison, officials said. “Franklin was found unresponsive in his single cell on March 28 at about 7:20 p.m. Medical assistance was rendered and an ambulance was summoned. Franklin was pronounced deceased at 7:43 p.m. His cause of death is pending the results of an autopsy; however, there were no signs of trauma,” prison officials said in a statement. Franklin, 67, was convicted in 2016 of killing nine women and a teenage girl from 1985 to 2007. During the penalty phase of his trial, prosecutors connected him to several additional slayings. Detectives believe he may have killed at least 25 women. The killer, one of California’s most prolific, targeted victims who were generally young, vulnerable and, at times, ignored. The attacks failed to raise alarms the way other famous serial slayings by killers