There's been police involvement but they never saw any of the injuries. No statement ever given to police. Would call outs that ended with NFA count as evidence? Or a recording of an emergency call to police where violent raging can be heard in the background.
Separate from police, there's photos (but no proof how they happened), audio recordings including threatening to give a beating that wouldn't be got up from, and messages including threats to kill. Problem is these are mostly a couple of years ago. No proof of anything much from recently. Witnesses from some incidents but these people likely to not want to get involved. Also maybe a 111 phone call describing a quite bad injury but told call handler it was an accident.