Basically since I have no idea how to continue it I'm just going to say who kill Alu.
Yes it was Lesley.
The blonde hair was Harley's and was there to throw them off.
Clearly she can shoot Alu, she's a skilled marksman/sniper.
Reason Lesley killed Alu was because she was paid to, yup, I decided she'd be a mercenary.
Who paid Lesley to kill Alu? Miya.
Why'd Miya pay Lesley to kill Alu? It is because she found out he was gay.
Yes, emotions do usually end up blinding people to the point of murder. Crimes of passion are always the bloodiest.
Zi was going to tell YSS in the next questioning.
In the end Lesley just throws Miya under a bus. She makes a plea deal and goes to court against Miya.
Lesley earns a lighter sentence than Miya in the end.
Added little detail, the ones to take in Nana is Clint and Layla. Because Layla and Miya still were friends even though they were fighting over Alu.
So this should hopefully give a satisfying end to the murder mystery. It was pretty sucky writing on my part.