I'm not sure I agree. He was a detective. He would know what wounds are. If he in any way attempted to conceal them, either by sleight of hand with crime scene images or cajoling a pathologist - arguably, he deliberately, knowingly contributed to the framing of a person, when evidence pointed away from that person.
But this brings me to another point: wounds can be missed and overlooked, even by experienced detectives, crime scene officers and pathologists.
I have to say, I am not entirely sure which photographs you are talking about. You did send me a link, but that was a general link to an entire thread, so I am at a disadvantage in this discussion as I am not clear what wounds precisely are being referred to. It would be really helpful if somebody could start a new thread for this discussion with the photos in the original post, so we can all see what is being talked about.
However, if I am right, I think you are talking about cuts to her arm. If so, those wounds would have been relatively minor in nature (the key point for the defence is not the severity of the wounds, but the type, location and number of them), and these wounds would have been covered or obscured by dried blood and so maybe for that reason not reported initially at the scene. It is easy to miss cuts and abrasions if slight or minor. I think an honest pathologist could quite easily have missed such evidence.