Former Beverly Hills 90210 star Luke Perry has signed on to join the cast of Law & Order: SVU after rejecting an offer to reprise his role in the hit TV series.Perry's former cast mates Tori Spelling, Jennie Garth and Shannen Doherty have signed up to appear in the forthcoming spin off series.But the 41-year-old actor, who has enjoyed limited success since leaving the show in 1995, has instead signed on to appear in the criminal drama's season premiere. The hour-long special will also feature guest appearances by Roseanne star Sara Gilbert and Lost actress Julie Bowen.According to celebrity blog PerezHilton.com, Perry will couple with Bowen to play a father accused of abusing their foster child.Just last month, the actor explained his decision not to take part in the show, saying: "I can't re-imagine it currently. It's just not something that I've thought about to be quite honest, I don't see it happening".Perry's episode is set to air this September.