Possibly one or two. Both were clients.
The first was 16 when I met him. My colleague and I both felt uneasy in his presence, but he was also charming and we couldn't put our fingers on why. He mentioned that he had a youth offending worker, so we contacted the guy for a bit more history.
The worker told us that this teen had an escalating history of violence, and that he appeared to enjoy it. That he showed no signs of effective impulse control and appeared to have a very volatile temper, but that he had also planned violence in a very controlled way.
We declined the referral on grounds of risk. Three years on, he and another young man beat a shopkeeper to death and were found guilty of murder.
Another client was a very charming, intelligent, cultured man approx 30. He had a diagnosis of paranoid schizophrenia and was unmedicated and had not been unwell for several years (he said). I was gobsmacked when he told me he was a "pit fighter" (like a cage fighter but unregulated, apparently), as it seemed incongruous. His case was handed to a colleague when I went on secondment.
A few months later, after she had closed his case because he no longer needed support, she texted me and told to look at the local paper online. He'd been sentenced to 15 years for raping 2 women and was described as "someone who preyed on young, vulnerable women". We later heard that there had been several other rape allegations, but the CPS had only proceeded with the 2 that were evidentially strongest.
We'd been doing lone, home visits to this guy, and neither of us had had the slightest sense of anything like that. We were both really shocked. (Although in that gallows humour way that people in jobs that can be disturbing use, it was observed that we were neither young, or vulnerable!)