The MM thing is actually quite interesting - I don't really think we have got to the bottom of why he came into the picture. The police seemed to think it was viable that a hit man was involved - and IMO I don't think it came from JB . So did they say to JM - we think someone did make a call - we think JB used someone else in the house - do you have anyone he might know who would be up to the job?
They took it quite seriously with all the statements /finger printing / blood tests etc.
MM knew the inside of WHF because he used to visit on a formal capacity as well as a working one ??
The Bambers thought he was " a nice man " ?? They obviously had no idea of his pedigree

Who are we to know that his alibi was sound ? He could have got his girlfriend to spin a tale.
And why didn't he sue for wrongful arrest ?