I was reading a work of fiction (okay, it was a comic book) and they had a serial killer who had murdered a series of six people. Due to the circumstances of their capture, the prosecution just charged them with two of the murders, which could be most easily proven in court and they were given a life sentence.
Now technically, the other four murders were never officially solved - nobody was ever charged or convicted of those crimes. But the police must have closed the investigations and the legal system regarded the crimes as solved.
Is there a legal term for this where a person is known to have committed a crime but isn’t charged for it because they’ve already been charged and convicted of other crimes?