Since apparently his step-daughter (and Rachel's friend, allegedly) was named as the caller to 911, it does seem incredibly likely that this man sadly saw exactly what he's telling the media he saw.
That being said, if LE knew that he saw her laying there deceased, wouldn't they have told him to keep those details to himself, to protect the integrity of the investigation? If they did tell him that, and he opted to be interviewed anyway, he'd be facing some charges. If they never did tell him that, then what appears to be damage control by them (telling the media he never saw anything) makes plenty of sense.
I really do wish he would have never granted a single interview, for the family's sake