I know right! My parents' petition raised more than 100,000 signatures and it was discussed in parliament and refused. :-(
They have plenty of cctv in the shops on board.
It's a sad thing. Some 250 people a year go missing in similar circumstances. They are not the safest places to be. They are often huge numbers of people being moved around outside of any policing borders.

In my brother's case, they said they can't investigate because there is no evidence to investigate.

It's a sad thing and perhaps the closure my parents were looking for was in making it less possible for this to happen to other families.

Thanks for your compassion @tanbay.
:-)