James "Whitey" Bulger, a notorious Boston gangster on the FBI's "Ten Most Wanted" list for his alleged role in 19 murders, was captured Wednesday near Los Angeles after living on the run for 16 years, authorities said.

Bulger, 81, was arrested in the early evening at a residence in Santa Monica, said a law enforcement official who was not authorized to speak publicly about the case. The arrest was based on a tip from the recent publicity campaign that federal authorities had regenerated, according to the official.

Bulger will make an appearance in Los Angeles federal court Thursday. He faces a series of federal charges including murder, conspiracy to commit murder, narcotics distribution, extortion and money laundering.

The FBI informed Santa Monica police late Wednesday about the arrest, said police Sgt. Rudy Flores. The FBI had been conducting a surveillance operation in the area where the arrest was made, Flores said. He gave no details of the arrest.

Bulger was the leader of the Winter Hill Gang when he fled in January 1995 after being tipped by a former Boston FBI agent that he was about to be indicted. Bulger was a top-echelon FBI informant.

Over the years, the FBI battled a public perception that it had not tried very hard to find Bulger, who became a huge source of embarrassment for the agency after the extent of his crimes and the FBI's role in overlooking them became public.

Prosecutors said he went on the run after being warned by John Connolly Jr., an FBI agent who had made Bulger an FBI informant 20 years earlier. Connolly was convicted of racketeering in May 2002 for protecting Bulger and his cohort, Stephen "The Rifleman" Flemmi, also an FBI informant.

Bulger provided the Boston FBI with information on his gang's main rival, the New England Mob, in an era when bringing down the Mafia was one of the FBI's top national priorities.

But the Boston FBI office was sharply criticized when the extent of Bulger's alleged crimes and his cozy relationship with the FBI became public in the late 1990s.

He has been the subject of several books and was an inspiration for the 2006 Martin Scorsese film "The Departed."

During his years on the run, the FBI received reported sightings of Bulger and his longtime girlfriend, Catherine Greig, from all over the United States and parts of Europe. In many of those sightings, investigators could not confirm whether it was actually Bulger who was spotted or simply a lookalike.

But in September 2002, the FBI received the most reliable tip in three years when a British businessman who had met Bulger eight years earlier said he spotted Bulger on a London street.

After the sighting, the FBI's multiagency violent fugitive task force in Boston and inspectors from New Scotland Yard scoured London hotels, Internet cafes and gyms in search of Bulger. The FBI also released an updated sketch, using the businessman's description of Bulger as tan, white-haired and sporting a gray goatee.

On Monday the FBI on announced a new publicity campaign and accompanying public service ad that asked people, particularly women, to be on the lookout for Greig. The 30-second ad started running Tuesday in 14 television markets to which Bulger may have ties and will air during programs popular with women roughly Greig's age.

The new campaign pointed out that Greig had several plastic surgeries before going on the lam and was known to frequent beauty salons.

Bulger, nicknamed "Whitey" for his shock of bright platinum hair, grew up in a gritty South Boston housing project, and went on to become Boston's most notorious gangster. He led the violent Winter Hill Gang, a largely Irish mob that ran loan-sharking, gambling and drug rackets in the Boston area.

After he fled, he became one of the nation's most-hunted fugitives, charged in connection with 21 murders, including the slayings of businessmen in Florida and Oklahoma. With a place next to Osama bin Laden on the FBI's "Ten Most Wanted" list, he had a $1 million reward on his head.

Bulger's younger brother, William, was one of the most powerful politicians in the state, leading the Massachusetts Senate for 17 years and later serving as president of the University of Massachusetts for seven years.

For many years, William Bulger was able to avoid any tarnish from his brother's alleged crimes. But in August 2003, William Bulger resigned his post as president of UMass amid pressure from Gov. Mitt Romney and Attorney General Thomas Reilly.

His resignation came two months after he testified about his brother before a congressional committee. William Bulger said he spoke to his brother shortly after he went on the run in 1995, but said he had not heard from him since and did not know where he was hiding out.

The committee, in a draft report issued in 2003, blasted the FBI for its use of Bulger and other criminals as informants, calling it "one of the greatest failures in the history of federal law enforcement."