justanotherflyer
In my law enforcement experience, it would be very unusual to find any signs of duress, blackmail or threats at the victim's house.
Such threats are likely to have been verbal, rather than written, and delivered personally by the blackmailer.
Zaharie would also not have been the ideal target for a blackmail attempt. He had 33 years in the job and was clearly devoted to it. He would be highly unlikely to have sold his employer, risked a beloved aircraft or the lives of hundreds of passengers.
There is also the question of planning. A theft of this nature would require a lot of long-term planning. First, I would imagine that it would not be known for sure, until the last minute, which aircraft the cargo they were after would be on. Second, I don't know what sort of rostering system MAS runs for its crews, but he would probably not have known his exact roster until a couple of weeks before this flight departed.
All of these factors make me think that a hijacking is more likely than crew stealing the aircraft. What may be of more interest are PAX who bought tickets close to the date of departure.