Hello. I am a solicitor with 20 years experience. I will try to answer this for you.
I think it is the crime side of this yo want help with.
If there is a police investigation gong on then he should wait to be contacted by the police. The like to do things in the order they want to and int he time that they want to. It is not as if there are many complicated acts to remember just a normal night's work then ended normally so he doesn't need to writ things down to help him remember the facts.
If the police do get in touch they may want to interview him. If they do want to question him then he has a right to free independent legal advice. There is no means testing for legal aid in the police station if they are arrested or being questioned voluntarily. Everyone is entitled to free advice. This can be provided by the duty solicitor scheme or he can instruct his own solicitor of choice.
I hitnk that her is really very little that you or he can do now except wait calmly for developments, that may never happen.