FBI agents and an Australian mediator are making what are believed to be unprecedented visits to Antarctica to investigate an assault and staff dispute at two bases.

They will be visiting a region whose harsh winters have a history of sending people over the edge.

The Australian Antarctic Division confirmed Sunday it was sending a mediator to the Casey base to deal with an “interpersonal dispute.”

An official denied a rebellion had broken out among the 15 staffers and said the base was functioning normally. The mediator, however, was to stay on through early January, when the next relief ship is due.

Meanwhile, three FBI agents were expected Sunday at the U.S. Antarctic base at McMurdo Sound to investigate an assault case.

The agents will take the alleged assailant into custody, according to an announcement to McMurdo staff by Stan Wisneski, the area manager for Antarctic Support Associates, the company that staffs and supplies the base.

A fight broke out between two cooks in the galley on Wednesday, in which one attacked another with the claw end of a hammer. A third cook who tried to break up the fight also was injured.

The victims were Tony Beyer and Joe Stermer, according to Wisneski’s announcement, which The Associated Press obtained from sources at McMurdo.

“Both victims required stitches, but should recover fully,” Wisneski said.

The suspect, who has not been named, has been held in custody and watched around the clock, he said.

The case provides a novel legal test for the FBI, since it appears to be the first time the United States has sent federal law enforcement officials to a U.S. Antarctic base to investigate a serious crime.

It is unusual, if not unprecedented, for nations to send law enforcement officials and mediators to Antarctica, which, under the Antarctic Treaty, belongs to no nation.

Routine offenses usually are dealt with by refusing to renew a staffer’s contract or a scientist’s grant, in effect exiling them from Antarctica.

Visitors who taunt the penguins and seals, remove rock samples or break other strict environmental laws are normally handled by the station’s chief scientist, who is a deputized U.S. Marshal.

Stress induced by harsh winter conditions on the continent has been known to take its toll on residents and explorers of the Antarctic.

In the 1950s, a violently deranged staffer at Australia’s Mawson base had to be locked in a storage room for the winter months out of fear for the safety of the rest of the employees. Only the base doctor could safely approach him.

The doctor at Argentina’s Almirante Brown station on the Antarctic Peninsula couldn’t stand the isolation as winter closed in during 1983. He forced his own evacuation, and that of his colleagues, in the only way he could: He burned the station down.

One of the Soviet Antarctic staffers in the past got fed up with a colleague over a chess game - and killed him with an ax.

Finn Ronne, a Norwegian immigrant who was the leader of a private American winter expedition to Stonington Island barely escaped being killed in the 1940s, according to the group’s doctor.

Dr. Don McLean, frustrated with Ronne’s authoritarianism and iron discipline, barely restrained himself from pushing Ronne off a cliff when the two of them inspected bird nests on a nearby island.

“I never came so close to killing anybody in my life,” he said, quoted in a magazine story on the Stonington expedition.