Police were investigating the disappearance of a venomous snake from an aquarium in Galveston, Texas, and said they believe the reptile has been stolen.
The 10-inch African bush viper was last seen Thursday evening at the Moody Gardens aquarium.
Officials said the fastener holding a padlock on the snake exhibit appeared to have been tampered with and damaged.
The snake's venom is not deadly to humans but could cause serious health problems.
Staffers have taken X-rays of three vipers to make sure they did not eat the missing snake.
The same snake went missing for two days last month. Workers found it hiding on a metal screen sealing the top of its enclosure, but cannot explain how the snake got up there.