I second everything Hair says:). It can be a pain, but I'd really keep after the humane society to keep after him. And I'd check with the vet too to see how on the up and up the guy was with you.
Policing is no fun, but sometimes we just have to bite the bullet and do it. We had a similiar incident around here, and you just have to be consistent with keeping after the officials.
Becky
Definately follow up with the vet.
I drove by frequently and drove up the driveway of my 'friend' with the starving horses. I had told her I would. I said I wanted to see full water troughs, recent farrier work, hay in the barn, and evidence of hay in the paddock. I never talked to her again, I just drove up and looked.
She only had temporary custody of those horses, she was keeping them for someone who was working in Alaska for a year or two and would return. When they returned and took the horses back, who did not look too bad by then, I shared with them what they had been through.
I still drive by there once in awhile, just to make sure she doesn't have horses again.
Follow up on the vet.... That conversation will mean everything. If the guy is telling the truth, you can relax a little. If you get no comfort from that conversation, then it's time to take your pictures, and your information, back to the Humane Society woman.
I know you are a bit afraid of pissing him off, I understand and would feel that too. But let me share this insight, from a cop who I talked to about this when I was discussing my fears of retalliation (remember the guy who dumped all the trash next door illegally? I had a bunch of pictures of him doing it. Pictures he'd know I took).
He said people who are trying to evade punishment don't make waves. They don't seek revenge, if that guy thinks you have something on him, he'll go out of his way to avoid you, and yours. Strangers you turn in for neglect like this don't usually seek revenge... Revenge comes from righteous indignation and they don't have that.