Hi Nissan,
The jobs rings alarm bells. I'd practice maximum caution. Strictly legally, you can investigate criminal matters, but some extra caution should be exercised especially with AVOs.
The issue is that if there's an AVO against the man, you can be pretty sure it's not a miscarriage of justice, but that the man did some things that warranted the AVO. He beats women or threatens to harm them.
I always recommend maximum caution when it comes to men involved in domestic situations. I wouldn't trust anything the client says and although I don't believe it's a matter of having a legal obligation to obtain instructions from a solicitor, I think it's very wise. If, and it's a big if, I were to consider taking the job, I'd want instructions from his solicitor, clearly spelling out what's to be done and what the objectives are. But even as I write this, I am thinking no, no, this job is bad news.
You see the problem is that your actions, say speaking with witnesses that are known to both parties of the AVO, might in itself be deemed a breach of the AVO (i.e. intimidation, coercion, harassment, etc).
That's my view of it, anyway.
BG