San Diego, CA -- (Sports Network) - San Diego Chargers linebacker Stephen Cooper will miss the first four regular-season games for 2008 for violating the NFL policy on steroids and related substances.

Cooper tested positive for a stimulant recently added to the NFL's list of prohibitive substances.

In five full seasons with the Chargers, the University of Maine alum has complied 259 tackles (178 solo), seven sacks and three interceptions.

Cooper is eligible to participate in the team's off-season program and in all preseason practices and games, as his suspension will begin Saturday, August 30 and run through Monday, September 29 following the Chargers' game against the Oakland Raiders the day before.