Other than self defense and acts of war, killing another human is murder. Whether the victim is a killer himself does not matter.
because they serially kill the people following them
you call the police.
we called police and they catch them
police is to catch bad people
he was a sidemann
with a baseball glove
you don't, that's the police's job
Unfortunately, not all killers are caught, even with today's advanced technology. To catch a killer like JTR the police would need some of that technology but it was not available for almost a century. They used the tools that were available but it was not enough to stop this particular killer.
Well you can get a FREE ride in a police car if the police catch you.
If he can catch up.
Speeding will result in a fine, if the police catch you.