a suspected bank robber facin police with a straight rayzor. here's marci gonzalez. >> reporter: tonight, investigators going frame by frame through this cell phone video and others shot by bystanders in miami beach as an attempted robbery suspect armed with a straight-edge razor was shot and killed by police. >> i saw the guy fall down and everything. >> reporter: investigators haven't said why one officer decided to use deadly force while another fired a stun gun. in this image you can see the filaments hitting the suspect just a moment before he's killed. >> a police officer on the street literally has a fraction of a second to make the determination whether deadly force is warranted. >> reporter: police identifying record of bank robbery. officers confronted the man after he walked into a bank of america yesterday morning and allegedly handed this note to a teller demanding money claiming to have a bomb. police say he then took off with no cash and ran into this nearby barber shop. coming out grasping this barber's razor. leading to the dea