Thank you for the info.
I'm not sure that could be it.
I am still in the beginners area and never seen pirates launch fighters.
If the host ship is wanted then it's highly improbable that its SLF would not be. Also not likely to be a passenger on the Anaconda - other than passenger liners I don't think NPC's carry passengers.
What most likely happened is that at some point you shot a clean NPC ship by accident, and it was subsequently destroyed by other NPC's, but because you shot it within a certain time frame you get credited with the kill. Just the same way that if you help destroy a wanted NPC, even though you don't necessarily get the last shot in you will get credit for the kill. That said, you should have had an assault bounty first, but it's possible that in the heat of the battle you missed it.