Example: A policeman found a pack of cocaine next to me, but I told him that drug had nothing to do with me. What I mean is: I was not connected to the cocaine at all.
On the other hand, my friend Charles (place the opposite expression here).
What expression is the opposite to "have nothing to do with", considering that my friend is connected to the drug somehow?
Edit: since my first example was a misconception from what I was trying to ask, I brought another context. The asnwers given helped me understand another definition, though. Thanks to everyone who pointed out I was wrong and to those who answered before this edit and helped me anyway.