“extreme strength and a high tolerance to pain”
Sounds similar to what Angel Dust did.
A few weeks ago a couple were stabbed to death. When police arrived he was eating the face off one of them. It took multiple cops to control him because of his strength and indifference to pain. In this current case one of the victims hit him in the head with a baseball bat while the other victim was wrestling him to the floor, it had no effect.
This stuff is bad news.