bottom. in an instant, the suspect approaches, fires. the victim s down. the killer sprints off. this 2009 gangland shooting in juarez, mexico, was captured from 10,000 feet about 2 miles up. you can see a whole group of people here reacting to the shot. they come over and look at the victim then they run down the alleyway actually after the shooter. reporter: from their specially equipped cessnas, ross and his firm persistent surveillance systems can monitor large sections of cities. because they re in the air for hours at a time, they can track back to the moment of a crime and before it. in juarez they meet up three to four times prior to the murder including one time right outside the murder scene. reporter: in the moments afterward we can follow all of the cars. we re going to jump over and follow the car that the shooter got into and see where he goes to. reporter: they tie in a google view image to show the house where the suspect went to