Joe Morgan died in September.

Two others:

Patrick Rose, who appeared in the famous season 17 segment in New Orleans of the drunk or high individual in the bar who got maced several times and fought with the police violently after. He died in 2017, possibly from MS complications. He had retired and had moved back to the Cleveland area, where he was born.

Hans Wagner, who appeared in season 22 segments in Houston, died at 35 in 2012, of complications from a head injury in a crash. He initially survived the crash, but the headaches never went away and he passed in his sleep.

David Michaud of Sacramento (Season 6) sadly was killed in a plane accident back in 2009, he lived to be 53, I thought he always acted very calm and professional when dealing with the public.

I just recently found out that Officer Pat Logan of Pittsburgh (Seasons 3 & 4) passed away in 2013, he was 66 years old, I'm really saddened that he's no longer with us because Pat Logan was always good humored and a lot of fun to watch, I like how he's able to mix humor with his no nonsense personality when it comes to dealing with the public, Officer Logan was always one of my favorite officers of the series.

I'm not sure if his name was ever mentioned but Fort Worth Officer Garret "G.W." Hull was murdered by a robbery suspect back in September 2018, he appeared in one Season 17 episode where he and John Ost did a search warrant on a known crack house.

I feel horrible for Officer Hull and his family that his life had to end the way.