To be fair, in the double jeopardy case, McCoy said he would charge him (he implied it was difficult but doable, although real life it shouldn't be that difficult). Besides, that was a fairly light-hearted episode anyway.
Which episode was that?
I forget all the plots, but it was one of those episodes that focused on the detectives as they dealt with a bunch of cases. One of them was about a pregnant girl who was kidnapped, another was that one. In that case, it was actually his brother who committed the crime in the end, so the double jeopardy idea was moot.