MIAMI -

A Miami-Dade Circuit Court judge granted a new trial for a 19-year-old man accused of shooting a police detective during a gold chain robbery.

The new trial for Willie Barney will start May 20. Jurors convicted him of attempted murder and robbery on April 25.

During jury selection for the first trial, Barney's attorney wanted to back-strike one of the jurors but the judge wouldn't let him. It was determined post-trial that the judge should have allowed the back-strike, opening the doors to a new trial.

Barney shot Miami-Dade Police Det. Wislyn Joseph in the chest outside a church in Miami's Little Haiti neighborhood on Sept. 22, 2012, according to prosecutors. Barney and two others robbed Joseph of his gold bracelet and his gold chain his late grandmother left him.

Joseph administered his own first aid, then called in a description of the suspects. Investigators have linked them to several other gold chain robberies.