Who referred you to the abuse unit?
As this type of crime is a common law crime there is no time limit on reporting or for it to be prosecuted. So you should in my view take this further to protect you and your family in the future. Happy to discuss further. I hope that helps. Please leave a positive rating so that I am credited for my time.
If you do report it then there is every possibility that he will be charged. From your initial question I thought that was what you wanted to happen. If not, then do not take it any further.
It would be for the police to assess whether there is sufficient evidence to charge him. If you have a witness then presumably there is so you should report it.