Snipped for focus.What does make sense is the SIL. He was with her that night. Dropped her off. I think there is a strong possibility he discussed $$$ with her. She said no to his request. He dropped her off. Stewed about it for a few hours. Maybe had some drinks. Went back to her place to try and change her mind and things got out of control. Or he could even have went back to her place later on to end her so that he and his wife would get their share of the inheritance. To me that makes the most sense to me, and the simplest explanation.
The ransom is either him trying to buy time and give a fake narrative of what happened, or just some idiots who are trying to take advantage of the situation.
Often the simplest explanation is the correct one.
Agreed regarding the opinion of the ransom requests, too.
LE are most likely building a case and that can take time ?
Imo.