On csi miami, what is the episode in which Calleigh's boyfriend kills himself? the characters allude to it...?

Question

but I cannot find it on-line. It's driving me crazy!

Answer 1

I beleive you are talking about the character John Haygen?  He shoots himself right after talking to Calleigh at the lab in the season 3 finale, 10-7. Haygen and Calleigh weren't dating at the time, but it was hinted they had a relationship in the past.

Here's the "10-7" episode summary:

While investigating the murder of man hired to make dirty bombs that terrorists intend to set off in Miami, Horatio finds the bloody fingerprint of his brother, Raymond, who he believed to be dead. However, when Raymond's son is kidnapped, he emerges from deep undercover and the estranged brothers must work together to save the boy. Meanwhile, while processing a crime scene, an unknown assailant holds a gun to Calleigh's head and, after a deadly confrontation in her gun lab, she is left doubting that she can continue as a CSI.