rogerio monitors the population regularly. declined by half in the past 15 years. >> that its not a happy face. now that we locked eyes with one of the creepy little creatures. we are simultaneously terrified and mesmerized. and despite their recent decline, it won't be hard to find more. we are entering snake alley. scientists estimate that almost anywhere you set foot a gruesom three feet away. golden lanceheads thrive here because they have no predator. their fast acting venom will literally burn through your flesh and cause you to bleed to death. one of the riskier on-camera things i have done. if one of these were to bite us, we would have six hours to get off the island. >> yeah. >> to a hospital. >> up to. >> up to. we could die at 2:45. >> yeah, probably. it's up to six hours before you die. >> keep an eye behind me. >> reporter: at this point, my producer, nick demand reinforcement. it's getting close. i don't like that. >> she is getting extr xting ex. >> reporter: come here, snaky. it is scary just filming these sna

rogerio is a man on a mission.see snakes right now, you're saying there are snakes here? >> oh, yeah. we have to find them. >> reporter: scientists estimate that almost anywhere you step foot, a gruesome death is lurking no more than three feet away. they are a formidable beast of prey, whose fast-acting venom will literally burn through your flesh and cause you to bleed to death. one of the riskier on-camera things i've done. if one of these things bit us, we have six hours to get off the island and to a hospital. >> up to. >> reporter: up to? >> yeah. >> reporter: so, we could die in 2:45. >> yeah. probably. >> reporter: for centuries, the sea has put a distance between the killer snakes and the rest of us. but now, rogerio is convinced somebody is actually stealing the snakes from the island. it's scary just filming the snakes. i want extra pay today. it's hard to imagine who would be crazy enough to steal them. why would you steal a snake? >> the pet market. >> reporter: people keep these at pets? >> oh, yeah.

the golden lance head is now critically endangered which has made rogerio fiercely protective of thisto save human life. there are more things related to you than you can imagine. >> reporter: dan harris, abc news, new york. >> diana, i think you need to follow up that story with a visit to snake island. i know how scared of snakes you are. >> i don't think so. >> you prefer the rodent to the snake, correct? >> i will do a snake and a rat before i do a cockroach. >> oh, it's the bugs that get you worse. >> cockroach island is not for me. >> if i go to snake island i'm wearing a medieval knight suit, not like dan harris. i'd wear chain mail. >> i'm surprised dan wasn't wearing the space shoe. like head to toe. he seemed way too comfortable in deadly snake environment. >> i think on my feet i would feel better with some steel. >> i don't want to be anywhere near that island. feel better with some steel. >> i don't want to be anywhere near that island. steel. >> i don't want to be anywhere near that island. she loves to shop online with her debit card. and so does bill, an identity thief