Published: Aug 19, 2010 3:14 PM EDT
Updated: Aug 19, 2010 12:15 PM EDT

JACKSONVILLE, Fla. (AP) - A teen has been convicted of fatally stabbing a Jacksonville man during a robbery.

A Duval County jury found 16-year-old Thomas Diquan Partlow guilty Wednesday of first-degree murder. He faces a mandatory life sentence at a hearing scheduled for Oct. 4.

Prosecutors say Partlow stabbed 49-year-old Grady Lane Williamson in January. Partlow and two other boys were driving around when they reportedly decided to rob Williamson for gas money. When the boys searched his pockets after the stabbing, all they found was $3.

A judge previously sentenced 17-year-old Gibson Wright III to 30 years in prison and 15-year-old Marvin Tony Clark to 25 years. The had both pleaded guilty to second-degree murder.