[quote=@Marx]
[@Letter Bee]
Harper will only realise that something's up with Ruby when he recognises that something isn't right. Is the security room within say 50 meters of Ruby? If so then Harper would have a chance to detect Alto, but if that's not the case then he would be none the wiser until he's aware of Ruby trying to make her escape.
[/quote]

The security room is within 50 meters of Ruby.