One poisonous bite from the Golden Lancehead pit viper is enough to kill a grown man within a few hours. It’s fast-acting venom will burn through flesh and cause its victim to bleed to death.

Rogerio Zacariotti, a researcher with the Cruzeiro Do Sul University in Brazil, travels to “Snake Island” regularly to monitor the Gloden Lancehead population. He is convinced poachers are stealing the snakes from the island and selling them on the black market.

Zacariotti allowed "Nightline Prime" to accompany him and his team on one of his research trips to "Snake Island," where ABC’s Dan Harris had some too-close encounters with the deadly snakes.