Samantha saw someone in a dark hoodie, like Emily's.
Jacob heard Mr. Smith arguing before the murder,
The forensic report shows the killer was hurt
Bike tire tracks near the alley suggest a quick escape
Emily's argument with Mr. Smith and her threats give her a reason to kill him.
Alex confirms Mr. Smith was in the area just before the incident.
Emily's denial and blaming someone else point to her trying to hide her guilt.
The torn fabric matches Emily's hoodie, putting her at the scene.