Did anyone interview her friends? ask if there was drinking? because if there was that changes things.
I think it was the Hugo, and that Kerkowski was not involved at all, and that Hugo needed a reason to kill Kerkowski. The evidence is unclear, as Weakley had infact researched Song’s case before calling the police which is weird because why would he do that? thats another mystery. was it to cover up for Hugo? or did Weakely just want to be involved. But I also have a theory that it could have been her roommate, Stacy. Stacy could have lied to the police and said that she did take Song home, but in reality Stacy killed her. Since Stacy was Song’s friend, she could have had a spare key to Song’s house, and got in to place Song’s stuff in there so it seemed like Song’s had already entered the apartment after Stacy had left.