Asbestos Drama, who is to blame, Real Estate, Electrician, Tenant or us?

I'm after opinions/advice about a "potential" asbestos contamination and who's fault it potentially is.

Real Estate engages, electrician to fix downlights in the property. Electrician has to cut bigger
holes for the new lights, which we were never made aware of. He doesn't clean up as he goes along so tenant does.
At the end of the process tenant (That was already renting there when we bought the property) finds a small piece of asbestos on the floor so goes
into panic mode.

The old ceiling is asbestos (The agent knew this) but when the house was renovated (before we bought) a false gyprock ceiling was put in under (not directly on to) the asbestos ceiling and assume down lights
were put in then and would have been cut in to the asbestos as well at the time.
Could a small piece have fallen out when electrician was installing the new
lights? electrician denies cutting into asbestos, of course but also arranged
the house to be tested with swabs done and it came back negative. The tenant
didn't like that as the report mentioned "preliminary" test.

Tenant left the house at the time of realising there could be asbestos and called the agent, THEN an hour or so later goes back in, goes into the roof cavity (without approval) with a mask and gloves on and starts
handling the asbestos debris. He has videoed himself up there for approx 6
minutes. Playing around with it, tapping pieces and trying to break at bit.
Then leaves the ceiling cavity with gloves, mask, clothing and a few pieces of
asbestos and lays them down in the house. The agent advised us of the potential contamination almost 2 weeks later. Tenant has involved safe work and they have wrapped the agent over the knuckles.

Tenant hasn't stayed there since but all his belongings are still there "Contaminated"
according to him. He hasn't paid rent for a month and claiming refund of rent
he did pay at the time and reimbursement for all his belongings. Which we get if the place was contaminated by the electrician but it's the tenants word against the electricians.

We were willing to spend the few thousand dollars to get the place fully tested but then realised there is no proof the electrician did anything wrong but video proof the tenant was playing around with the asbestos etc, so we don't think we should pay for anything due to his negligence. Even if the place is contaminated there is no way of knowing exactly who did it.

Any helpful professional or non professional opinions welcome.