I discovered that an ex-colleague I worked with within a "toxic" team is now interviewing at the place I work now. What do I do ?
Context: So a year ago I joined company A as a contractor to join a team of 5 people, in which the work atmosphere was really toxic, basically everyone was disliking each other and trying to badmouth/blame every one else as soon as they could. For instance :
- talking badly about other colleagues at lunch when they are not here
- complaining to my actual employer that the work didn't go fast enough
- complaining to my actual employer that I didn't do X even I was told to, while I actually was never told to
- complaining to my actual employer that they had spent a week trying to fix some bug I caused, while they never told me about this during normal work (I was basically sitting next to them so I would probably have directly heard of it if I had broken everything)
- telling me that if colleague X was being nice to me, he was actually not genuine because he was badly talking about me being my back
I jumped ship after 9 months because this was unbearable, just in time when they were trying to fire me for incompetence. Since then they went through 3 contractors that they fired for the same reason.
The good news is, my new job is very interesting and the work atmosphere is extremely good.
This week while arriving at work I bumped into an old colleague of my previous job who was waiting to be interviewed at my new company. We exchanged a few words, where basically he told me the company/team I used to worked for was falling apart, several people were fired and he was probably going to be next. He also told me that he wasn't one of the person who wanted to fire me (I know it's a lie) and invited me to lunch.
I have no part in the recruiting process and I'm not even supposed to be aware he is doing interviews, so I'm not sure how out of line I'd be to go ahead and talk to HR about how I don't like this guy and I think we shouldn't hire him.
On the other hand... I do not think that he would be a good long term employee for my employer, and that he could have a toxic effect on the atmosphere in the office.
How can I communicate this most effectively to the hiring team?