There were two couples and one guy in the carriage we were in yesterday on the FR1 train from FCO to Trastevere.
We were at the back with our luggage crammed into the seat with us. A guy got on and walked down towards our end of the carriage I held onto my case (yes, I am paranoid) and he went to get off but sat down again.
I didn't think about him again until, as we pulled away from the next stop, the couple down the other end started swearing - the guy had picked up one of their cases and got off the train with it. They couldn't do anything about it cos the train had taken off again.
That couple had put their luggage on the seat as they walked up to the top level and then sat in the next seat along but looking back towards us rather than towards their luggage.
My husband is now just as particular as me about being careful with our belongings. I am not trying to be alarmist but just trying to warn people to be careful with their luggage.