Esta pergunta já foi feita antes, mas parece que a resposta mais razoável é essa, de @ chaitanya89:
The way I've seen it is, As soon as the bad guy's car crashed, Lou took his camera and started filming and Lou observed that the bad guy is injured and gaining senses and recovering, he wanted to use this situation and kill his partner. So, he backed off and asked his partner to come shoot with steady hands and zoom. Unlucky for the partner, when he reached in front of the car, the bad guy recovered and not thinking straight and shot Rick, at this point, gangster would have shot Lou if he was there. But after shooting Rick, when he saw Lou standing there filming without a budge, the bad guy was surprised for Lou's audacity and few moments later Police arrived and the gangster's main concern is to deal with the police who shot the gangster's partner down.
Você pode ler mais sobre esta página .
Pessoalmente, eu vejo isso como o gangster estava caindo em si após o acidente e Lou percebeu isso e recuou em direção ao carro da polícia, para que ele pudesse se esconder atrás dele se visse o gangster puxando sua arma. Ele não podia necessariamente saber o que o gângster faria quando chegasse, mas teve uma chance e disse a Rick para gravar o incidente, sabendo que ele poderia muito bem ser morto.