Updated

Washington Redskins defensive end Jarvis Jenkins was suspended for the first four games of the 2013 regular season for testing positive for a banned performance-enhancing substance.

Jenkins, who played in all 16 games last year, apologized for his suspension. He was slotted as the starter this season.

"It's an obscure substance that I've never even heard of, and I still don't know how it got into my body," Jenkins said. "My only guess is that it came from one of the supplements I was taking around the time of the test, even though none of them listed anything banned.

"I'm very sorry for the effect of this situation on my teammates and coaches, and I also apologize to my family and all Redskins fans. I will be very, very ready to contribute as soon as I get back for Game 5."

The suspension, which is without pay, means Jenkins can participate in training camp practices and preseason games, but not in the first four regular season contests. He won't be eligible to return until Sept. 30, the day after a game at Oakland.