Where to go from here

I've had an issue with an ex colleague who has been harrasing me for months now. He was fired for an incident where he threatened me and used a bunch of racial slurs (we are both white but he was referring to another co-worker). Turns out he was listed as fired for racism only.

I had a couple months without issue and forgot about it, then out of nowhere he slashed my tyres which I reported. He was on camera walking up to my car and a witness said he was acting shady but 6 months later the police still havent acted.

It's been months since and there's been at least a dozen incidents (that I didn't think to record) where he's cussed me out on radio or hurled abuse out his window and once where we came face to face at a servo because I didn't recognise his work vehicle and he got right up in my face threatening again.

Today he's done it again but mentioned drowning me at a location near where my wife works and I'm getting concerned he's stalking me.

Where do I go from here because reporting it to police doesn't seem to solve anything and he just gets more pissed off. He's fairly unhinged and has spent time in prison for beating supervisors and coworkers before.