FBI agents return to the scene of the mass shooting...

FBI agents return to the scene of the mass shooting at the Pulse nightclub in Orlando, Fla., on June 14, 2016. Credit: AP / Joe Burbank

This story was reported by Anthony M. DeStefano, Kevin Deutsch and Robert E. Kessler. It was written by Zachary R. Dowdy.

The failure to stop the Orlando, Florida, nightclub gunman from his deadly rampage shows the difficulty of preventing terrorists and particularly lone wolves from striking within the United States, said sources familiar with the investigation, officials and experts.

The FBI is challenged by limited manpower, the huge number of possible suspects and the overwhelming number of potential locations for attacks, they say.

There are anywhere from 800,000 to more than a million people on the government’s terror watch list, according to sources.

“People who think this [a watch list] is some kind of panacea, just misunderstand what the watch list is all about,” said Matthew Levitt, director of the Stein Program on Counterterrorism and Intelligence at The Washington Institute for Near East Policy.

Omar Mateen, 29, killed 49 people and injured 53 at the Pulse nightclub on June 12 before he was fatally shot. Mateen had been placed on the watch list while he was investigated by the FBI in 2013 and 2014. He later was removed from the list after investigators could not find any terrorist connections or criminal activity.

Boston Marathon bomber Tamerlan Tsarnaev, and Major Nidal Hasan, who attacked and killed 13 soldiers at Fort Hood, Texas, in 2009, also were known to the FBI. Tashfeen Malik and Syed Rizwan Farook, who killed 14 in a terrorist attack in San Bernardino, California, were not on the watch list.

Mateen’s name had been on the central watch list of known and potential terrorists that is updated daily and shared with local, federal and international law enforcement agencies. Names on the list come from foreign and domestic investigations.

The list consists of a series of databases that law enforcement agencies — but not private employers — can consult and, if necessary, take action.

Since its formation in December 2003, the FBI screening center that oversees the list has made strides in becoming the central point of contact for law enforcement looking to identify terrorists. But as a review in 2007 by the Justice Department’s Office of Inspector General discovered, the watch list has had problems with completeness and accuracy, with some names excluded that should have been on the list.

More than 1M believed listed

The list has grown from 150,000 people in April 2004 to 400,000 in February 2006 and then to 724,442 records as of April 2007, said the review. Now the list is more than 800,000, sources said, and experts believe that number has swelled to more than 1 million since the rise of the terror group ISIS and the civil war in Syria. FBI officials won’t give precise numbers.

The watch list has many different categories and uses. For instance, inclusion on the no-fly list portion of the list will keep a person off a commercial flight, while a person on the “selectee list” will be subjected to enhanced screening at the airport.

Nidal Hasan, the perpetrator of the 2009 shootings that killed...

Nidal Hasan, the perpetrator of the 2009 shootings that killed 13 at Fort Hood, Texas, was convicted on all counts on Aug. 23, 2013. Credit: Getty Images

The Department of Homeland Security will also use the watch list to screen people applying for visas. Local law enforcement can tap into the list to check on arrest warrants to see whether someone is the subject of active intelligence investigations.

Once the FBI ends an investigation with no further action, a name will be dropped from the watch list.

Staunch defenders of the bureau say that it is unfortunate, but sometimes, even with every effort, investigations do not work out.

Shawn Henry, a retired executive assistant director of the FBI, said the Mateen case will be thoroughly studied to see what can be learned from it.

But, Henry said recently, as far as he is aware, the agents “did what they are supposed to do. . . . They did what they could do.”

Brothers, from left, Dzhokhar and Tamerlan Tsarnaev in the crowd...

Brothers, from left, Dzhokhar and Tamerlan Tsarnaev in the crowd watching the Boston Marathon on April 15, 2013, the just before the bombings that killed three people and injured 264 others. Tamerlan Tsarnaev died in a shootout with police; Dzhokhar Tsarnaev was sentenced to life in prison for his part. Credit: AP

Mateen came to the FBI’s attention after co-workers reported that he had made threatening remarks in his workplace. After an investigation, officials determined that he was venting about perceived anti-Muslim bias and determined that he was not a threat, said FBI director James Comey.

To investigate Mateen, dozens of agents conducted surveillance on him, wiretapped his phone, culled through his garbage and dispatched informants to gauge his appetite to commit crimes, Comey said.

“Our investigation involved introducing confidential sources to him, recording conversations with him, following him, reviewing transactional records from his communications, and searching all government holdings for any possible connections, any possible derogatory information,” Comey said.

A law enforcement source said one of the things the FBI examined during the two investigations over 10 months was Mateen’s potential connections to Moner Mohammad Abusalha, the first American to carry out a suicide bomb attack in Syria. Abusalha, the bomber, at one point had lived in Fort Pierce, Florida, where Mateen also lived.

A link Mateen had to Abusalha was also found to be unsubstantial, said Comey, prompting the removal of Mateen’s name from the watch list.

Tashfeen Malik and Syed Farook, pass through customs at O'Hare...

Tashfeen Malik and Syed Farook, pass through customs at O'Hare Airport in Chicago on July 27, 2014. They died in a shootout with police in December 2015 after killing 14 people at a party in San Bernardino, Calif. Credit: AP

Material being re-examined

Now, officials are doubling their efforts to re-examine material they had gathered in the two abandoned probes, said a law enforcement source who added that those investigations led to some leads and a paper trail that federal authorities are scouring as part of the nightclub shooting probe.

“We are going back and looking at all of our contact with him . . . to determine what, if anything, could have been done better,” U.S. Attorney General Loretta Lynch said.

Rep. Peter King (R-Seaford) believes that the watch list should expand to include people who voice sentiments that he said show “terrorist inclinations,” a category that wouldn’t drop a person from the list just because there was no evidence of criminality.

“I think ISIL [Islamic State] is trying to recruit unstable people, angry people — that means we have to have a category like that,” King said.

The FBI is flooded with tens of thousands of tips about possible terrorist suspects and only has about 1,000 agents directly assigned to such anti-terrorist operations, officials said. At any one time, the bureau has about 1,000 active anti-terrorist cases, officials said.

Omar Mateen of Port St. Lucie, Fla. in a photo...

Omar Mateen of Port St. Lucie, Fla. in a photo from his Myspace page. He died in a shootout with police after killing 49 and wounding many more early June 12, 2016 at Pulse nightclub in Orlando, Fla. Credit: /

Since it often takes 36 agents to do full-time surveillance on a single suspect, officials said, it would require 36,000 agents for full investigations of the pending cases, while the FBI has about 13,000 agents.

“If somebody wants to assassinate the president and is willing to die, he might succeed,” said a source. “How do you protect thousands of nightclubs, malls, supermarkets, sporting events?”

The deletion of Mateen’s name from the watch list didn’t mean that he wasn’t dangerous, experts said.

The challenge, said Levitt, is how to keep tabs on people locally who express anti-social or dangerous sentiments even if they are not on the watch list, while preserving civil liberties.

The American Civil Liberties Union has criticized the watch list, saying the information on it “is often stale, poorly reviewed, or of questionable reliability” and there is “no meaningful process to challenge mistakes.”

But others say that because of civil liberties concerns it is harder to investigate locations and who to single out to investigate.

For example, King says agents and police have complained to him that they are getting signals that they shouldn’t be “as aggressive as possible” as they wish to be in investigating potential terrorists in the Muslim community, for fear of offending other Muslims.

Managing such a list also creates thorny policy issues, said Victor Asal, associate professor of political science at the University at Albany.

“If I went online to tag everybody who said something dangerous or threatening online, can you imagine how many people we would have to follow?” Asal said.

“The government is going to make mistakes when you have lists of many thousands of people,” said Jordan Tama, assistant professor of international relations at American University. “Mistakes also about information not being shared properly.”

A pilot program being run by the Department of Homeland Security in Boston, Los Angeles and Minneapolis uses psychiatrists and social workers who can take over and approach people like Mateen who can’t be prosecuted for their statements but need to be headed off before they take violent action, Levitt said.

“That is where the rubber will meet the road,” Levitt said.

Steven Dubovsky, chairman of the psychiatry department at the University at Buffalo, said that dangerous people signal their intention to do things because they don’t see any legal consequences to such expressions. But monitoring such behavior raises constitutional issues requiring oversight, Dubovsky said.

Robert Strang, head of Investigative Management Group, a security and intelligence firm, thinks that it might be time to have one cohesive enforcement unit to combat terrorism, much the way the Drug Enforcement Administration was formed in the 1970s as the go-to agency for combating drug trafficking.

Such an agency would be the repository of all intelligence and watch lists, said Strang, who served in the DEA in the 1980s in New York.

“I think we need to streamline all these investigations,” Strang said.

Tactics to find ‘lone wolf’

Some critics say the FBI’s emphasis on investigating people with links to terror groups is unfit to tease out the “lone wolf,” a person with no direct connection to such groups, but who is willing to carry out horrendous attacks and invoke the name of a group such as Islamic State.

Michael German, a retired FBI undercover anti-terrorism agent, said that the lone wolf — whether a member of the Ku Klux Klan or someone supposedly loyal to Islamic State — is typically not ideological, but a seriously disturbed person who latches onto an ideology to justify his or her hostile emotions.

The error that is being made by the FBI in general is assuming that if someone does not have a proven connection to a group, as was the case with Mateen, he is not a threat, said German, who is now a fellow at the Brennan Center for Justice at the New York University School of Law.

The focus should be on whether the person has a violent personality, and is capable of acting in the name of the ideology, German said.

John Cohen, who coordinated counterterrorism activities for the Department of Homeland Security and is now a professor at Rutgers University, agrees with German’s assessment that a productive law enforcement model also would concentrate on the stability or mental health of a potential lone wolf, rather than just on seeking a direct connection to terrorist groups.

One possible model is how the Secret Service deals with people who are seen as a threat to the president, even if there is not enough information to arrest such individuals, Cohen said. That agency has a tradition of assessing the potential for violence of such people and referring them to mental health professionals and religious leaders in their community, Cohen said.

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