First I thought the method is the key here and very important:
1. Miss Everett and Mrs. Randall were bound, gagged,and strangled...but the robbery wasn't important, the killer didn't steal anything...he/she is a psycophath. The first killer.
2. Mr. Fowler and Mr. Wilbanks stabbed to death, after robbery...drug-related, the cash was important, not the murder. The second killer.
3. Mr. Hannah was beaten to death, because he knew/saw/heard something, no robbery, he was poor. Beat, later burn somebody is much personal...Mr. Hannah knew his killer. The third killer.
No!!!
Phelps: 5 victims, 5 killers. Me: 5 victims, 3 killers. But since then police arrested Mr. Wilbanks' killer and Mr. Fowler's killer too, two different guys.
The other three murders are still unsolved, maybe related, maybe not. Sometimes a killer use different methods, for example: Zodiac Killer (Arthur Leigh Allen?) shot his victims and later stabbed a taxi driver in 1969 (and earlier stabbed a college freshman girl, Cheri Jo Bates in 1966).
Best witness is the dead witness. For the killer.
Take care of vulnerables: elderlies, children, ill and disabled people! (And animals.)
Mississippi Five - Elderly Murders (1996-1998):
https://www.wtva.com/content/news/Elderly-residents-murders-still-a-mystery-after-20-years-455875173.html
https://eu.clarionledger.com/story/news/local/2017/05/24/arrest-made-columbus-cold-case/342218001/
https://cdispatch.com/news/columbus-man-arrested-in-14-year-old-murder-case/