A St. Clair County jury has convicted a 23-year-old East St. Louis man of killing a teenager nearly three years ago.

Trenton A. Jefferson was found guilty of first-degree murder in the shooting death of 17-year-old Marcus Gosa of Washington Park, according to a news release from St. Clair County State's Attorney Brendan Kelly.

Gosa was shot once in his back in the early morning hours of April 10, 2010, in an alley between 44th and 45th streets in East St. Louis.

The jury deliberated about 90 minutes before returning their verdict of guilty.

A jury trial in September for this charge ended in a mistrial after the jury became deadlocked.

Kelly thanked Assistant State's Attorneys William Clay, Judith Dalan, the Illinois State Police and the East St. Louis Police Department for their efforts in the investigation and prosecution of this case. "Persistence was key. "(Assistant State's Attorney) William Clay in particular had great passion for this case," Kelly said.

This trial was presided over by the Circuit Judge John Baricevic. Jefferson is scheduled to be sentenced on April 17.

Jefferson, who was convicted the day after his birthday, faces a mandatory prison sentence of between 20 and 60 years in the Illinois Department of Corrections. At the request of prosecutors, Jefferson's bond was revoked and he will remain in the St. Clair County Jail pending sentencing.