Just get every piece of evidence you can and fight!

In our own properties, we have gathered empirical evidence that providing tenants visibility into their resource consumption almost always leads to reduced resource waste {we still get the odd tenant who simply does not care and would rather set the thermostat at 28C than don a sweater}.  

They like evidence and documentation.

Just can't shake the stigmas.I would definitely go over there to get photographic evidence if you don't have it.

The tenant has the burden of proof to their claim by submitting evidence such as maintenance record requests, photographs, and/or testimony.

A SFH I own was being re-prepped to re-rent and was being advertised by the PM company.Who, as is ever increasingly more evident, apparently do whatever they want, often ignoring what I tell them to do, and then if it's ever questioned they have a version of The Story which makes it all my fault.

Should he encourage the existing tenant to call the police/gather more/better evidence?

All they are interested is in EVIDENCE!!!!!!

My experience with both of these companies is while they don't present empirical evidence of the rent values , they both have excessive resources and when comparing the rent values they present to the properties already in my portfolio they are pretty accurate. 

You just need evidence in writing that shows what your agreement is.