Did he lose his hair?
I was channel surfing and saw Adrian Zmed's face on what I think was an old "Murder She Wrote" episode and it triggered my distant memories of TJ Hooker. After looking him up on IMDB I see that he's been doing voice work for the most part this century.
I always thought he would have been active in TV well into the early 2000s either doing cop dramas or comedies but he didn't.