It's not a chase unless you run. If you run, you look suspicious. At that point, he can call the police on you, which he didn't even do. He called the non-emergency number. Seemed to me like he truly was suspicious.
Had he just said "Hey man, look, I live right up the road here I'm staying with so-and-so" there would have been no further confrontation. But when he took off running, all that did was make someone already suspicious looking even moreso. Had a cop been the one watching him, the cop would have pursued. Martin has a right to run, and Zim has a right to follow. M shouldn't have jumped on top of and beat up Zim. Zim was armed. Ol travvy is dead. If you're going to beat on a cracka beat on one that ain't packin heat.