First: your art is great and your dialog is great too, your storytelling is thrilling and you have a good rythem.
I‘m a writer and a real life security officer and have an understanding of how police work works. I can’t promise how much I can help but I see some plot holes and logic that I like to point out.
Why take the blood to compare with the witness, if the witness doesn't have a scratch?
The witness is not allowed to take the drawing, that is stealing evidence, even if it was fake evidence.
This you probably have some good answers to but if you want to discuss ideas I’m open.