So, last night, a WSer (sorry I've forgotten your name - PLEASE add more to this discussion if you can)...reminded us all of the Danny Rolling case (Gainesville Ripper).
This serial killer (who killed up to 5 people in one setting and over a fairly short period of time, IIRC) did not know his victims and instead apparently looked for situations that met his criteria for easy kills. He admitted later that there was a sexual assault component to some of these killings, but I don't know if that was the case for the 5 students he killed (decapitating only one of them). He had been on a burglary spree.
He used a military style Ka-Bar knife.
His crimes were spaced out, geographically and it took some good noticing by police that the crime in Gainesville was connected to another similar crime in Shreveport. One key part of catching him was that he said "deeply disturbing things" to a woman who invited him over to dinner after meeting him at church. She reported it to police.
After capture, he said his motivation was to "become a Superstar like Ted Bundy."
Author Sondra London wrote a well-researched book about it, The Making of a Serial Killer.
For me, this comprises an entirely different set of scenarios than ones I've posted about earlier. He also made sure his victims were silenced by applying duct tape while they were sleeping and then killing them, IIRC. He took the duct tape with him in most cases and died by lethal injection.