Cincinnati, OH -- (Sports Network) - Cincinnati Bengals linebacker Darryl Blackstock received a four-game suspension Tuesday for violating the NFL's policy on performance-enhancing drugs.

A fourth-year player out of Virginia, Blackstock is eligible to return to team activities on November 10.

"I've apologized to my coaches and teammates for an unfortunate mistake," Blackstock stated. "I did not intentionally violate the policy, but I know it's my responsibility to use only approved nutritional supplements, and I didn't realize I was taking an over-the-counter product that included a banned substance. I also want to apologize to our fans, and I'll do everything I can to be ready to come back strong next month."

The winless Bengals (0-5) also re-signed running back Kenny Watson to the active roster and signed cornerback Simeon Castille to the practice squad on Tuesday.

Watson, who was Cincinnati's leading rusher last year with a career-high 763 yards, had been released by the Bengals this past Saturday.