5yo making up lies

[2kids1me]

Hello
So my sons dad is a pathological liar! My son sees him once a week but recently spent 4 days with him over Xmas.
My son came back and claimed my other half hurt him, and upon questioning admitted he lied!
Naturally I listened first as I always try to believe him but then said he was lying and didn’t know why?
Now I explained he cannot make up such lies as he will get someone in trouble and he said he tells his dad my partner hurts him!
I don’t know what to do, i feel like this is something to do with his dad?
Any advice?

My son done this at the same age. Told his school I had scratched his face (he did have a scratch but it was casued by his younger brother) school reported to SS. I never did get to the bottom of why he lied. Maybe an attention thing?

Logically there is only one thing you can do. Make sure the communication between you and your ex partner is water tight.

Unfortunately the communication between us is minimal as it was a horrific relationship, which started being mentally abusive once my son was born. I should have said this, and this is why I fear his dad is involved in these lies. Hopefully it’s just for attention and I chose not to give him any for it. He got a speech and then I left it as I did think if this is for attention he certainly won’t be getting any!