IF I were LE - I would get the names of all of JLM's family, have someone on staff look up land owned by them past and present.
Look for connections, grudges, losses, arrests, imprisonments, etc. that might be connected to locations of bodies in any of the disappearance cases that JLM may have committed.
Look for perceived injustices, connections to historical figures such as George Carr the alias used by JLM in TX, who was brother in law of Thomas Jefferson and may have owned slaves.
Find out about old family grievances:
Did JLM's father become an alcoholic because of a job loss? If so, who fired him?
Did his mother get hurt by someone who owns the Quarry or another potential place that JLM might take HG?
Did his grandfather die because of stress due to some legal or property problem or lack of medical attention?
MH was found on land owned by a super-big wig in county politics - longtime head of the Zoning Board.
Did JLM place MH there to embarrass or exact vengeance on Mr. Bass?
Did someone in JLM's family lose their property or its value because of zoning, taxes, etc. due to a decision by Mr. Bass?
Was JLM angry not to be invited to the Seven Mile Sleepover? Or was he there?
Was there a connection to Bass and JLM's family?
Did Mr. Bass or one of the new property owners of the subdivision refuse to let JLM fish on his creek banks?
Did JLM kill Cassandra Morton and place her ( a drug user, etc.) on Liberty U. property on purpose to embarrass the school for ousting him for his behavior?
A grudge with a psychopath or sociopath can be real due to some event small or large or...imagined or just feeling 'dissed' by someone.
My working hypothesis is - The abductions/kills are spontaneous, unplanned, a matter of opportunity, and there seems to be no stalking ahead of time, but the deposition of (some of the) bodies may be intentional and motivated by vengeance because of JLM's or his family's grudges.
ADDENDUM - Another question for LE
Did the artist/musician daughter of Mr. Bass (forgot her name) where the Seven Mile Sleepover was held, or any of their friends get a ride in JLM's taxi to the Bass farm where MH was discovered?
JMO