donno. but the events or memories that flashed in MC head the night somehow indicates MC had a hand in that but he cant remember. since Alexnader had molested both women he might have snapped and we see a flashback him throwing his gun at the beach then taking it back. and it is clear that Sarah's gun was used to kill alexander but when the MC put it back in drawer it disapears so im guessing the killer or the witness might have taken the gun. my 2nd guess is Aiko. since she clears the room /and my favorite character in game/
It is the mc (and the players) who assume(s) that Alexander was shot ... the police just talks about him being killed or dead.
"I'm investigating the death of Alexander Jones."
"I've got evidence placing her [Sarah] at the University on the night Alexander was killed."
Sarah has a blackout so she does not remember anything (which might be caused by the combination of her meds and alcohol).
mc is drunk and at the beach. The University is 30 min by car away. why and how would a drunk mc go to University, kill Alexander there and then return to the beach? mc doesn't even know where Alexander lives. And the round is missing in Sarah's gun. I don't know if any shots were fired with mc's gun at all.
And even to go back and kill Alexander in Sarah's house the mc already had spent too much time at the beach and is too drunk to use a gun.
The "flashbacks" are probably just dream sequences where mc explores how to save Aiko or alternative outcomes.
First "flashback" picture has the voice of Kate : "No ... mother ... Please" and Sarah is happy and wears her top.
Second "flashback" picture has mc's voice and shows likely mc's gun. Alexander is quite happy ...
When mc wakes up at the beach he has his gun in his hand probably drawn while dreaming ...
Dev is just playing with the players by adding these images ...
Note :
If mc gives Sarah the gun in her office (afternoon) it seems that the "The GUN" story line will be aborted and Sarah's arrest will never be triggered and the game will be stuck in a dead end.