At least six dolphins have been killed in the Gulf of Mexico, and officials are determined to find out who is responsible. These attacks were brutal, one dolphin was shot with a handgun, others had parts of their bodies chopped off and one had a screwdriver stabbed into its head.

Officials have put out a warning for people along the Gulf Coast from Louisiana to Florida to be on the lookout for anyone approaching wild dolphins. The person responsible could face up to a year in prison per dolphin killed.

Jane Velez-Mitchell spoke to marine mammal expert and  Ric O’Barry, star of the documentary “The Cove.” Ric has offered up $5,000 in rewards for anyone with information on the attacks on dolphins. Ric also runs dolphinproject.org and you can follow him on Twitter.

For more on this story, watch Jane Velez-Mitchell weeknights at 7 p.m. ET on HLN.