My son had a similar experience except fortunately he was not killed but severely beaten. It amazed me at the time that the bad guy continued to use the phone. I was in such shock that it took me about 36 hours to realize I could contact my provider and shut down the phone but in that time I was able to get all the phone calls he had made and give that information to the police. The phone was never recovered and I don’t know whether the cops used it to locate him but they did and at the time he was, I believe, also wanted for questioning for an armed robbery of a quickie mart. The bad guys girl left her phone and we got a lot of information off of it too.
How awful for your son. I hope he is ok now.
We had a similar case here in Pgh where two gang bangers who were still in high school attacked a guy with a concrete block and stole his phone. Fortunately, they were so dumb they used it to upload photos of themselves in the HS, and the victim was able to see this through his photo account somehow. That’s how the cops tracked them down.