Lonnie David Franklin Jr., a serial killer who preyed on Los Angeles’s forgotten women for years before being brought to justice, died Saturday on death row in San Quentin prison.

Known by the nickname “The Grim Sleeper,” Franklin came to public attention thanks to the dogged investigative efforts of LA Weekly reporter Christine Pelisek, who broke the wall of silence erected around the case by authorities.

Prison officials confirmed the death in a statement. “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.”

Franklin flew under the radar for several decades. It’s believed his killing spree ran from 1985 to 2007, and police believe he may have killed at least 25 women. He was convicted in 2016 of killing nine women and a teenage girl.

Because Franklin targeted prostitutes, drug addicts and other vulnerable women, his killings didn’t attract the same attention as those of other serial killers like the Night Stalker or Hillside Strangler.

Police did not bring the cases to public attention, and the media was largely indifferent, allowing Franklin to continue to operate in relative anonymity. However, some of the slayings were linked through ballistic and genetic evidence, but the DNA that would definitively prove a connection was elusive. Police offered a $500,000 reward for information to help catch the killer in Sept. 2008.

In 2010, state offender records finally yielded a partial DNA match of a close relative of Franklin, leading police to begin to focus on him and his relatives. A police stakeout of Franklin’s father that saw them recover a partially eaten piece of pizza finally led to a match.