Prosecutors formally charged a police officer with felony first-degree assault for an alleged attack on a teenager suspected of consuming alcohol.

Sixteen-year-old Juan "Willie" Vasquez's family said the teen suffered a lacerated liver, broken ribs and kidney injuries when the officer jumped on his back up to four times.

Forty-year-old Officer Charles Porter, who had been assigned to the gang bureau, was arrested May 8 on suspicion of second-degree assault. Prosecutors filed the more serious charge Monday, saying the attack happened after Vasquez was in custody.

Vasquez has undergone at least two surgeries following the alleged attack April 18, according to his family.

A police report says at least two police officers witnessed the incident that followed a foot chase when Porter allegedly saw Vasquez consuming alcohol.