I’m leaning towards abduction now, initially MM may have believed Samantha had an accident, but later realised it could have been connected to something going on in their lives, possibly business wise, or they received a “message “ from someone after he had been to the police.
It would explain the apparent half hearted press conference,MM was probably told to say as little as possible, and dont answer any questions, as it appears the wider family has also been told.
This would also explain why they are so anti the media.