[fifield]

Tough call, both could develop well...

If it were a close friend committing the murder, the story would probably develop more naturally focusing on the tension between the friendship/loyalty and protecting his own ass/risking jail time. So, potential for more character development, more meaningful story, less mindless popcorn-action.

If he were doing something wrong at the time, what would it be that he'd be doing? Would it be something that would frame him as the murderer? This could develop into more of an action, ElD on the run to save his life and bring the real murderer to justice type story, where he'd use his immense knowledge of the city to avoid capture.

The murdered could also be someone he knew, even if vaguely like a first date or something, to make it personal. He'd have the struggles with the city cops who can't get a lead, then just say [censored] it and take justice into his own hands, of course finding the necessary leads to hunt down the murderer and avenge his friend's death. He'd be able to have that sweet montage where he dresses in layers, looking all sharp, throws on the shades even if it's dark, and clips his 2" .38 in his waistband, then looks in the mirror before long-striding out his door. Soooo many options.