If that is case then it won't be so hard for him to prove ownership of 1 account and other users to prove ownership of their accounts, right? Besides, he said he is living with 300 people and they all share 3 computers it means that IP is the same. Is IP the same?

To be honest this looks like 1 person, but I could be wrong:





Also it is very strange that 2 newbie accounts, sorry, 3 accounts were created within 48 hours. They all just found bitcointalk? I don't think so. Email conversation is much longer than 48 hours, and accounts signed up on 14,15 and 16. Feb so I think it is very strange that they all signed up and complained at the same time:

Name:    bowlerman
Position:    Newbie
Date Registered:    February 14, 2018, 11:37:04 AM

Name:    jborn
Position:    Newbie
Date Registered:    February 15, 2018, 10:36:51 AM

Name:    dude0001
Position:    Newbie
Date Registered:    Today at 06:44:50 AM

But as I said I can be wrong with this.

So, I think it is best to wait fraud department to finish with investigation, if everything is fine then there won't be reason to hold his/their funds.