Thanks all for the replies. If there's no crime history then guess I'll just have to be a bit more careful when there's lots going on around me to think about, plus I've never really been in a similar situation so I was a bit panicky at the time, anything could have happened. I'll check my in-game logs to see if anything can be found there. I appreciate everyone trying to ascertain what may have happened but I wouldn't be able to confirm if anyone is right so I'll be leaving it at that, however, I have replied to some of your responses.
A couple of quick side questions:
Do the feds turn from green to red on the radar when attacking CMDR's?
Does using a Kill warrant Scanner with fast scan modification also speed up the regular scan?
Good to know, this is the first time I've ever given in to their demands. I'm think one of them made an initial demand which I ignored hence their attack, a 2nd made a later demand which is the one I responded to to try and save my butt. I guess it was too late by then.
I've shot fed ships by accident a few times recently without response but yeah, it's possible I shot a clean ship. Would the feds attack me for an unsustained stray shot on a clean ship?
I only mentioned a 'haz res (high)' so yeah it was one of them and I'm 100% allied with the controlling faction in that system. I was doing a massacre mission on a rival faction's members and it was them who tried to rob me (I have 0% rep with them).
I don't and wouldn't even know where to begin with that site's tools!
I've had the bounty for maybe a month now and since then have visited the very same system to do massacre missions on the same faction's pilots without incident a few times. Happily bounty hunted alongside the feds, using them as support so I didn't think my measly 200Cr bounty was a concern.
Do you know if they scanned you? If you have any kind of bounty anywhere, and any cop or bounty hunter scans you, they will go for you.
Unless I've been too careful in the past?!
But seriously, the cops won't normally scan you unless they're bored. You wouldn't show as wanted there as I don't think your bounty was with them. But, if you have a dormant bounty from elsewhere, and they scan you, the result will be what happened for you.
I know you're not overly concerned now, but I thought I'd write this out for you for future help really. In other words, if you ever have a bounty, either expect this to happen at some point, or better still - if you go dock in a low security system with an Interstellar Factor, you can pay it off then and it's cleared. Let me know if I can explain that bit in more detail mate