OK there must be a language barrier here, so I will try to explain more clearly.
At Nav Beacons & RES sites, there are a mixture of NPC ships that spawn - some are Wanted, some are Clean, some are system security. If you shoot at the Wanted ships, you are within the law. However, from time to time, one of the Clean ships, or system security ship, may be accidentally shot by you. In the early days of Elite, this would result in YOU getting a wanted status, however the threshold at which you get the Wanted status has now been raised, so this happens less often now.
However, in my example I gave, the Cobra must have been at <10% hull when he flew between the guns of my Corvette and the Anaconda I was aiming at, causing it to explode, and causing me to get a bounty and notoriety.
Admittedly, this is an edge case, but since it's a real thing that happened only a couple of days ago, I felt it was worth mentioning.