Like I said, a threatening move changes things.
But if you have a teenage daughter and you find a scared teenage guy staring at the gun you're pointing at him, it might be a good idea to let your daughter know in no uncertain terms that if she really doesn't know this guy in her bedroom (GET A CLUE), that you just might shoot him dead, since he's terrified and might do something stupid, so - one last time - ask her if she knows him, and let her know you're going to find out the truth no matter what happens.
Anyone with half a brain would start thinking these things through before they killed someone, seeing as the IDEA here would be to try to resolve the situation WITHOUT killing anyone - right?
how do you know he didn’t ask her more than once during this time?
a reasonable person at 2am could easily believe the daughter saying she didn’t know the guy.