OAKLAND, Calif. » A former Oakland High School security officer has been convicted of felony assault for beating a disabled student in a wheelchair last year.

The Oakland Tribune reports that a jury on Tuesday found 24-year-old Marchell Mitchell guilty of beating Francisco Martinez.

Martinez testified that Mitchell punched him four times while he was handcuffed, kicked him and threw his wheelchair on top of him during the course of two attacks caught on surveillance video. The 18-year-old Martinez has cerebral palsy and uses a wheelchair.

Mitchell was encouraging students to get to class when he got into an altercation with Martinez. He could be sentenced to as little as probation and as much as four years in prison.