She was sent to rehab which didn't work.

I think the show has always been David Caruso's. Kim had a great gig going w/NYPD Blue & they had offered her the opportunity for Philly where she played an attorney. I loved that show & it got the hook. After leaving a very successful show I think that the people actually felt bad and wanted to find a home for our Kim knowing the public would be itching to see her and that's my guess why she was on CSI: Miami. I don't know why it didn't work out or if it was simply planned to put her face in the public eye again for a few episodes. The storyline on the show had that she was widowed and quit and then changed her mind and returned. It always left the storyline so that she could exit when she/they chose. I liked her on that show. I'm addicted to that show tooShe's incredibly talented.

I heard that she didn't get along with David Caruso, so the producers decided to let her go and keep Horatio.

In 200111c2 is the year she left CSI Miami, at that same time she was a arrested for drunk driving. harmittamber is right, it wasn't convincing at all, I believe they release her from her contract because she can't show up for work for court dates and all. The producers are no joke I heard.

According to episode 1.11, she resigned because the job reminded her too much her husband's death Barely convincing