Chad Holley was the first witness Thursday in the trial of former police officer Andrew Blomberg, who is charged with misdemeanor official oppression in the alleged beating. Blomberg faces up to a year in jail if convicted.
Security video from the March 2010 arrest appears to show several officers kicking and hitting the then-15-year-old Holley.
During opening statements, Blomberg's attorney called the ex-officer a hero and said he had been trying to secure a suspect.
Holley was later convicted in juvenile court of burglary and put on probation.
Blomberg and three other officers were fired and indicted.