I have two guesses:
The obvious; The wife did it because now he could afford more than one wife.
The less obvious; A male relative did it, with plans to frame the wife, hence the request by a relative for a fuller investigation.
“The less obvious; A male relative did it, with plans to frame the wife, hence the request by a relative for a fuller investigation.”
Bingo. That’s what I’ve thought from the gitgo. Frame the wife to get her out of the collection pool. If the victim lived, he would have gotten it all. Now with him, dead, the wife would get it, unless you could get her out of the way. The relatives were going after part of the winnings. They all had motive.