Authorities last week identified the killer whales seen attacking a great white shark off the Farallon Islands as members of the "LA Pod," a gang of orcas that usually frequent waters off Los Angeles.

Witnesses to the Oct. 4 attack saw two orcas swimming when the larger one sped off, returning to the surface with a 10-foot shark in her jaws.

The 20-foot orca was caught on videotape thrashing the shark to death. Based on the footage, biologists have identified the attacker as "CA2," a fullgrown female at least 25 years old. She was last seen off Santa Barbara in 1995 and is the only known killer whale to prey on sharks.

CA2 was first photographed off Los Angeles in 1982 and has been caught on film 18 times since then, said Alisa Schulman-Janiger, a marine biologist who tracks the LA Pod for the American Cetacean Society. It was Schulman-Janiger who recognized CA2 from the footage.

"She happens to have an extremely distinct dorsal fin with a deep notch at the base," said the biologist, who recorded the videotape off the news. "When I freeze-framed it, you could take out a picture and match it notch by notch. There was no doubt it was her."

Schulman-Janiger described the LA Pod as an "opportunistic" group that preys on whatever they can find. Although they are usually associated with Los Angeles, she said they have been sighted from northern Baja California to Monterey Bay.

The Farallones incident was their first sighting this far north.

Not much else is known about the LA Pod. They are not an offshore crew, living in open waters and feeding entirely off fish. Nor do they live and feed in a defined area like resident groups farther north.

However, the 15 or so whales in their pod still keep very close together.

And unlike most transient groups, which travel thousands of miles preying on sea lions and other marine mammals, members of the LA Pod are now known to also attack and eat large sharks.

"They kind of break all the rules," said Mary Jane Schramm, an Oceanic Society naturalist who witnessed the attack. Oceanic Society members have helped compile a catalogue of 260 recognizable orcas, which will be published this fall.

Schulman-Janiger said the attack footage was unprecedented but added that so little is known about the LA Pod that the incident only adds to their mystery.

Although the Farallon attack has brought the LA Pod considerable attention, she said their activities and whereabouts were unknown from 1991 to 1995. "I suspect they just went down to Mexico," she said.