34-year-old David Salasky, Jr. pleaded guilty Monday to 15 counts, including 2 counts of 1st degree murder, in the September 16, 2011 killing of 44-year-old Lieutenant Joseph Szczerba.
A sentencing date was not set.
Szczerba, an 18-year veteran of the force, was fatally stabbed while trying to arrest Salasky after a car break-in and foot pursuit. He was the first New Castle County police officer to lose his life in the line of duty since 1972.
According to court records, Salasky has both a long criminal history and a history of mental health issues. Defense attorneys suggested he was delusional and high on mind-altering chemicals when Szczerba was killed.
Salasky faces 2 mandatory life sentences without the possibility of parole and up to 153 additional years.
The Associated Press contributed to this report.