Nor would it help the friend as it provides another avenue for police to try to get information from.
My default has been that if any of my friends were to be accused and I were asked about it I would say that I didn't believe the rumor and drop it.
If I had secure communication with them that wasn't tied to either of us and I was certain wasnt compromised, I might send them a short note to let them know they aren't alone.
In most places, what your friend needs to do is get an attorney. If there's a chance of you getting dragged into it, you might want to get some contact info for one yourself. There's nothing wrong with having a good legal contact should you need one, it's smart and normal. Attorneys are best sought out when you don't desperately need them, check into their history and try to keep in mind that they might not be cheap, but are often worth far more than they cost.
Edit: It is probably a good time to examine your data, make sure there is no incriminating evidence. Ensure all devices are using encryption, etc and purge any unwanted data.