M
@mjwalker it sounds as if you're dealing with an immature speciman of the male species hereafter referred to as El Jerko. You have probably already had words with him.
You have a few options to consider and one piece of advice.
Document your observations and interactions with El Jerko in a CYA, cover your butt file.
Discover places he frequents outside of work. Enlist the help of a very large friend, sit down and go over your prepared notes with El Jerko. Calmly make it clear you will not tolerate his interference any longer. The implied threat may be sufficient to eliminate his bs.
Go to your manager with your CYA file. Present only the highlights and major issues, nothing personal, no feelings. Focus on impact of El Jerko's actions on the company.
Leave contaminated attractive food in the company fridge or on your desk. I'm guessing El Jerko is a thief.
Leave anonymous notes on his car, front door, social media Spread lies, innuendo, threats are prosecutable and would likely point back to you. Wear gloves, pretend you're in a movie but try to have backup to watch out for you and keep you safe.
Frame El Jerko, get nasty, devious, set him up then stand back and watch someone else "discover" the evidence.
