CHICAGO (AP) — A Chicago man jailed on alleged fabricated drug charges is suing the city for actions by several officers that caused him to languish in prison for years.

Jermaine Walker, who filed the lawsuit Thursday in U.S. District Court, was arrested in 2006 on a crack cocaine charge. His lawyers say four officers framed him during the course of their investigation, doing everything from planting drugs on Walker to hiding evidence.

After years of maintaining his innocence, a public defender pushed prosecutors to take another look at the evidence. They turned up witnesses who contradicted testimony by police that there was no camera in the alley where Walker was arrested. Walker maintained footage from the camera would prove his innocence.

Cook County prosecutors moved in March to dismiss the charges. A spokesman says city officials haven’t seen the lawsuit and had no comment.