A second teenager had pleaded guilty in the shooting death of a retired St. Louis police officer.

A second teenager had pleaded guilty in the shooting death of a retired St. Louis police officer.

The St. Louis Post-Dispatch reports that 16-year-old Justin Mathews pleaded guilty Thursday to second-degree murder, robbery and other crimes. Last month, 17-year-old Jalynn Garner pleaded guilty to crimes that included first-degree murder.

Retired Sgt. Ralph Harper was killed on Oct. 29, 2018, during a carjacking attempt. Harper was a 33-year police veteran who retired in 2007.

Mathews was 15 at the time of the crime and Garner was 16. Both were certified to stand trial as adults.

Mathews admitted providing Garner with a gun and waiting in a stolen SUV as Garner tried to rob Harper.

Garner faces sentencing Nov. 26 and Mathews will be sentenced Dec. 12.