Charles Cullen, the notorious nurse who allegedly killed as many 40 patients by injecting lethal doses of intravenous drugs, pleaded guilty to 13 murders and two attempted murders late last week, thereby skirting the death penalty. Cullen worked in nine hospitals and one nursing home – the Liberty Nursing Center in Allentown, PA — during his 16-year career before he was arrested last Dec. 12. The nursing home had told the Associated Press that it fired Cullen for “failure to follow company procedures.”

Cullen struck a deal Thursday to cooperate with authorities as they try to uncover other crimes he may have committed, in exchange for a life sentence without parole. Authorities would not speculate on how many deaths Cullen may have been responsible for in all, according to the Associated Press. He is to be sentenced eventually to multiple life sentences in each state and, according to the plea deal, will serve prison time in New Jersey. 

“We need to use Mr. Cullen and we need to debrief him to find out how he was able to accomplish what he accomplished,” New Jersey Attorney General Peter Harvey said.