SAN DIEGO — Antonio Gates’ squeaky-clean image took a big hit Thursday when the San Diego Chargers’ star tight end was suspended without pay for the first four games of the 2015 season for violating the NFL’s policy on performance-enhancing substances.

He will be able to return to the active roster on Oct. 5, a day after the Chargers’ game against the Cleveland Browns.

One of the NFL’s top tight ends for more than a decade, Gates has had a Hall of Fame-caliber career after joining the Chargers as an undrafted rookie in 2003 following a college basketball career.

“In my 12 years in the NFL, I have taken tremendous pride in upholding the integrity of the NFL shield and all that it entails,” Gates said in a statement. “I have taken extreme care of my body with a holistic approach and never taken any substance that was illegal or banned by the NFL.”