ST. LOUIS -- Prosecutors have dropped murder charges against a St. Louis 18-year-old who was to go on trial this week for a 2013 shooting death.

Tyrell Davidson was released from jail after prosecutors chose not to pursue his case. The St. Louis circuit attorney's office isn't discussing the matter.

Davidson was 16 when he was certified as an adult and charged with murder in the September 2013 killing of Chauncey Brown, a 16-year-old Sumner High School student.