AskHistorians

I hardly believe like the Roman empire had organized crime groups.

With organized life, comes organized crime.

Crime. Crime never changes.

I get they exist but usually you just here about on job and then nothing else. Why is that?

High profile assassinations by lone individuals usually end with the killer getting caught or killed. Usually not an action undertaken by someone of sound and professional mind. If you want to read up on the careers of long time hitmen, you can find books on them for sure, but the kinds of killings they do aren't usually national news.