Elissa McClain is the true main antagonist from "Deep Freeze", episode 6.05 of CSI: Miami.
She was portrayed by Dina Meyer, who also played Sally Larkin in Monk.
Elissa McClain is the wife of famous quarterback Doug McClain, who was found dead at their home after being stabbed in his neck. At the scene, Elissa prevented Alexx Woods from performing an autopsy, as she had made plans for Doug to be cryogenically frozen.
It was revealed later on that Rita Sullivan, one of Doug's many mistresses, stabbed Doug in his neck. She did so in a fit of rage due to Doug brushing her off when she begged him to get tested to see if he was a match for his biological son with Rita, who was later succumbed to a kidney disease. However, Rita's attack only paralyzed Doug; it was Elissa who actually killed him.
While Elissa was on the phone with a cryogenics company known as PreCore, she heard Doug groaning and found him with the knife in his neck. Instead of saving Doug, the evil Elissa pulled out the knife and intentionally killed him. She had become tired of Doug cheating on her and decided that he would be worth more to her dead, and as Elissa herself put it to Horatio, she played the role of the grieving widow after the deed was done. Elissa was later arrested for her husband's murder.