Gulf of Mexico Dolphin Killings Inquiry Escalates ATLANTA - An investigation into the mysterious killing of dolphins in the Gulf of Mexico is gaining momentum, with a federal agent now in charge of the case and a $30,000 reward for catching the killer or killers. This bottlenose dolphin, found fatally shot in the water off the Mississippi coast earlier this month, is one of six that have washed ashore in the area, mutilated or with bullet or stab wounds. Since the summer, six dead dolphins have washed ashore with bullet wounds, severed fins and jaws, and stab wounds. The latest was a dolphin found off the coast of Mississippi with its lower jaw missing. Whether the deaths were caused by the same group or person is not known, but federal investigators are turning to the public for help. The National Oceanic and Atmospheric Administration has called on fishermen and beachgoers to report any dead or injured dolphins. Forensic experts at the agency are testing the slugs removed from the animals to see if they come from the same gun. More than 700 dolphins have been found dead of various causes in the gulf since February 2010. But scientists say that deliberate, violent deaths are rare. "These are senseless, repugnant acts," said Moby Solangi, the executive director of the Institute for Marine Mammal Studies in Gulfport, Miss. These dolphins are mutilated in a way that no animal is in the wild. Rewards for clues that lead to an arrest have been offered by the marine institute, the California-based Animal Legal Defense Fund and Paul Watson, an early member of Greenpeace and an Animal Planet host. "I regard the killing of a dolphin as murder, and what we appear to have on the Gulf Coast is a dolphin serial killer," Mr. Watson said. I want this sadistic killer stopped. Much attention has focused on the role of fishermen. Dolphins often swim behind boats, eating shrimp from nets and waiting for unwanted fish to be thrown overboard. Fishermen say they become frustrated by dolphins" stealing bait or destroying nets. Louis Skrmetta, a ferryboat captain for Ship Island Excursions in Gulfport, said he had heard of fishermen firing guns at dolphins to keep them away. "When the dolphins show up, some of these guys get frustrated and consider them nuisances," he said. The deaths have been spread across the coast. In June, a dolphin was found stabbed with a screwdriver in Alabama. The others have been shot in Louisiana and Mississippi over the past few months, the authorities say. Under the 1972 Marine Mammal Protection Act, killing a dolphin is punishable by a fine of up to $100,000 and a year in jail. Investigators say finding the responsible person or group will be difficult, with the crimes spread across three states and no known witnesses. NOAA has received numerous tips but none that have led to a suspect. "We've had everything from anonymous faxes to anonymous telephone calls," said Jeff Radonski, the agency's acting deputy special agent in charge of law enforcement in the Southeast. We've had spouses that are mad at their husbands spout off. It's the regular gamut that a normal police officer deals with. Much of the business of wildlife sleuthing is similar to routine police work, he said. It is just harder. With strong tides in the gulf, a dolphin could be swept miles before washing ashore or could have been mutilated after reaching the beach. "The biggest problem we have is we can't go to the dolphins and interview friends and build up a history," he said. One of the key things in our investigation are witnesses, somebody coming forward, telling us what it is that happened. Campbell Robertson contributed reporting from New Orleans.