If they've got half an ounce of sense his friends are currently erasing any piece of evidence they can find and figuring out a way to disappear from the net if at all possible. General estimate is someone can hold out under trained interrogation (and I'm not talking about water boarding here, I'm just talking about someone who knows the psychology of the situation and the best tactics to use) for roughly four days. After that point they'll probably have enough information from him to go after the rest of them. They don't need him to turn and give testimony, they just need enough information to get to his colleagues and for there to be some evidence left they can use against them.
If there's no physical evidence left by that point then it's his word against the rest of them and that's not enough to build a case on. The smart things to do is to assume he's going to give the rest away and do whatever you can to reduce the chances of them actually being able to pin anything on you after he does so.
You'd assume anyway that he's actually been in custody for a while anyway - it's unlikely the police would make his arrest public immediately because his friends would be warned as soon as they did so.
Carry on doing whatever they were doing? The worst thing they could do.
