>> kaj larsen travels to a world few of us know about. >> and this new york city cop says he fired to save his father's life. but he would walk free after his conviction was overturned. so how did he end up back in prison? >> you must have been crushed, crushed when they told you you had to go back. >> revealing investigations, fascinating characters, stories with impact. this is "cnn present ous "with your host brooke baldwin and dr. sanjay gupta. >> good evening. the bloody drug war in mexico has gripped the world's attention. >> but way off the radar south of mexico is a region that's even more violent. >> in fact, it's been called the deadliest place in the world. >> the homicide rate in honduras alone has more than do you believed in five years. kaj larsen journeyed to the heart of the violence. >> reporter: in the past year over 17,000 people have been murdered in guatemala, el salvador and honduras. in honduras, over 90% of crimes like murder are never solved. they call it the impunity rate. i asked the chief of police in san pedro, the second biggest city here, if they would t

kaj larsen travels not front lines of a war few people know about. >>> twisted justice? >> i just saw him up with the bat and he started to swing, and that's when i reached for the gun. >> this new york city cop says he fired to save his father's life. >> i was convicted of second-degree murder. >> but he would walk free after that conviction was overturned. so how did he end up back in prison. >> you must have been crushed? crushed when they told you you had to go back. >> revealing investigations, fascinating characters, stories with impact. this is "cnn presents," with your host tonight, brooke baldwin and dr. sanjay gao give up gupta. >>> way off the radar, just south of mexico is a region that's more violent. >> the northern triangle of guatemala, el salvador, and honduras the deadliest place in the world outside of active war zones. >> in fact, the homicide rate in honduras alone has more than doubled in five years. cnn's kaj larsen journeyed to the heart of the violence. >> reporter: in the past year, over 17,000 people have been murdered in guatemala, el salvador

kaj larsen journeyed to the heart of the violence. >> reporter: in the past year over 17,000 people haveeen murdered in guatemala, el salvador and honduras. in honduras, over 90% of crimes like murder are never solved. they call it the impunity rate. i asked the chief of police in san pedro, the second biggest city here, if they would take us along with a call came in on a crime. ament later we got our wish. so we jumped in the trucks and we're headed there right now to see what's going on. >> it's completely real. we're not making up how violent this place is. we've been here four hours and our first body's turned up. he's been shot. the impact wound appears to be right here on the right side of his head. the police commissioner told us as is very typical in these situations, nobody saw anything, nobody heard anything and nobody knows this guy. >> nobody wants to talk, which suggests that people are definitely afraid in this neighborhood. as they should be. >> for years the region has been plague wd violent gangs started by gang members deported from california. but in the last few year

give us a sense of how it works when it comes to clearing mines or threats like kaj larsen?, michael, you're absolutely right. in fact, the program has been around since the '60s when it was a classified program that was designed to help them design a better torpedo, but they found quickly they had other skills that they could use like mine hunting. so what the dolphin or what the mammal does is it uses a very sophisticated form of biological sonar called echo location, very similar to what a bat does in the dark, and that allows it to paint a very accurate picture of an underwater object. from there the handlers work with the dolphins to determine exactly what a mine looks like, and it's a positive reinforcement training. in fact, i have a short video of one of the actual mine hunting dolphins doing that that you can roll right now to get an idea of what it looks like in action. >> over time, we have to train the animals to discriminate between -- you know, it could be a lobster trap -- sorry, got to pause it -- right now the animal just went positive. >> so what's she doin

kaj larsen takes us there.me of the pictures in this piece are very gruesome but are included to show how violent is the region has now become. >> in honduras, over 90% of crimes like murder are never solved. they call it the impunity rate. i asked the chief of police in san pedro sula, the second biggest city here, if they would take us along when a call came in on a crime. a minute later, we got our wish. >> so we jumped in the trucks and we're headed there right now to see what's going on. it's completely real. we're not making up how violent this place is. we've been here four hours and our first body has turned up. it appears that he's been shot. the impact wound appears to be right here on the right side of his head, and the police commissioner told us that you know, as is very typical in these situations, nobody saw anything, nobody heard anything and nobody knows this guy. [ speaking foreign language ] >> nobody wants to talk. which suggests that people are definitely afraid in this neighborhood. >> as