ST. LOUIS — The last of five defendants charged in a conspiracy to murder two witnesses to a teen's shooting death in 2013 has pleaded guilty in a deal with prosecutors.

Tyrell Davidson, 23, received a 12-year prison term Friday after pleading guilty to second-degree murder and armed criminal action. Prosecutors dismissed eight other counts against Davidson including first-degree murder and witness tampering. Davidson was given credit for time served in jail.

Davidson's trial had been set for later this month. His public defender could not be reached for comment Monday.

Charges against Davidson's four co-defendants were dismissed in September 2018 after a St. Louis detective's brain cancer diagnosis left him unable to testify. The detective later died.