Hypothetically speaking would you turn a blind eye to a crime if the person doing it can justify it?

Let say you are in a parking lot late at night, you see a portly middle aged man running with his brief case. Chasing him is a teen girl about 15 or so. The man runs between two tall SUVs and you hear him fall. The teen catches up and you hear screaming then the man’s voice pleading “No please don’t!” You heard 3 to 5 pops of a 9 millimeter with muzzle flash. The teen exit from between the vehicles and spies you. She rushes you and begs you not to call the cops or say anything but if you did say he was shot by a mugger. If she said she did it because he was a stepfather that was touching her since she was 11 and also raiding her college fund so she could not escape to college. Would you just get in your car and drive off? Would you lie to her and tell her you won’t say anything then when safe in your car call the cops? If you called the cops would you stick around until they showed or make the call then haul butt out of there. If you believed the guy was a scum bag would you avoid getting involved figuring he had it coming? Or the law is the law and the ends do not justify the means?