A previous coworker of mine was charged with aggravated assault last night after he had gotten into a fight with another female coworker(his girlfriend).
The key from this is charged with - unless you know all the details of the situation (and even then...) it doesn't make sense to begin gossip about this.
The coworker had worked in a position that reported to me at this previous company, and I'm still friends with many of the previous coworkers who work around this man on a day-to-day basis. Should they be made aware of these chargers, and his management as well?
If you aren't at the same company, it makes no sense for you to interfere.
An easy test is:
- Would I report the charge to this company if I did not personally know the people involved?
If your answer is, "yes, I believe there is a serious enough danger in them working together to tell a group of non-friends" then you should find a way to inform them (or at least the police). If not, then no, you really shouldn't.
Otherwise it's going to come across as spreading gossip - and rightly so.
It's not your responsibility to manage this guy nor his coworkers anymore, either, so keep this in mind.
While I would not necessarily suggest getting yourself involved directly, it may be wise to counsel the female coworker to bring it up to her management (and make better relationship decisions... but wrong SE for that...). They will be a lot more receptive to her saying, "my coworker assaulted me, what can be done?" than someone who no longer works there interfering.
Additionally, while you don't indicate how you know this information, I doubt it's going to remain private regardless of what you do.