ILPT Request: Some dude intentionally pees on my front door every fucking day

I’m tired there is someone that pisses on my door and my grandmas front door every fucking day he usually does it when there’s no more sun light, although some times we come back from eating lunch and there’s a pool of piss under my door. Idk how tf does he pee so much.
houses are together, the house faces a public street so anyone can walk there.
This guy is fucking sneaky and we have never been able to catch him (or her.
What can I do to either catch him or let him know that he should stop fucking with my family or else he will get hurt.
We have tried to do an electrical circuit that when he pisses the cables that stick out will electrocute him, but at the end it didn’t work.
We have also tried to put lights with movements sensors but the actual door is in a corner so he would be able to hide from the light.
I really don’t know what else could I do and my grandma is tired of this and feeling helpless.
Any tips or ideas are welcomed and will be thanked