The FBI's Terrorist Watchlist reportedly had over 800,000 names on it in 2014. Omar Mateen, who killed 49 people at an Orlando nightclub June 12, was once one of those names. Here's what you need to know about the Watchlist. (Monica Akhtar/The Washington Post)

Lawmakers are growing increasingly frustrated at the FBI’s decision to remove the Orlando shooter from the terror watch list in 2014.

And their concerns are fueling a new debate about whether the government needs to keep better track of people it once investigated in order to find out when they try to buy guns.

The creation of a secondary list for those who were once suspected of terrorist ties or activity could prove controversial. But some lawmakers note it’s the only way authorities could have known that 29-year-old Omar Mateen, who killed 49 people on Sunday in a nightclub popular with the gay community, had purchased a gun.

A secondary list would not in itself resolve the gun-control debate in Congress, where Democrats and Republicans are arguing over whether the government should be able to prevent suspected terrorists from purchasing firearms and explosives. But in theory, it could be used to at least alert the FBI if a former suspect, like Mateen, wants to purchase a gun.

The subject of whether to keep track of those once suspected of terrorist links was repeatedly raised in a Tuesday briefing for lawmakers on the Orlando shooting by FBI Director James B. Comey and Homeland Security Secretary Jeh Johnson.


Rep. Adam Schiff (D-Calif.), left, ranking Democrat on the House Intelligence Committee, left, and the panel’s chairman, Rep. Devin Nunes (R-Calif.), right. (Andre Chung for The Washington Post)

The House Intelligence Committee’s ranking Democrat, Rep. Adam Schiff (Calif.), said that lawmakers grilled officials on “whether someone who has been taken off the watch list should nonetheless trigger an alert when they go buy a weapon like an assault weapon,” adding that the subject is “one I certainly intend to pursue.”

But it is unclear exactly how the government would keep track of people once suspected of terrorist ties.

Sen. Dianne Feinstein (D-Calif.) has introduced a measure to deny weapons to those on the watch list as well as anyone else the attorney general suspects of terrorist ties — a category that could include individuals like Mateen.

But Republicans balk because they worry such a measure would infringe on the Second Amendment rights of those mistakenly put on the list, which is hard to get off.

“I’m all for having terrorist watch lists, but having said all that, if everyone’s on a terrorist watch list, it doesn’t mean anything,” Rep. Peter T. King (R-N.Y.) mused after attending the briefing, saying perhaps Mateen could have been put “on some kind of a quasi-list or something.”

Lawmakers roundly expressed frustration that the FBI had the 29-year-old Mateen, an Afghan American who was born in New York, in its sights before deciding he didn’t pose an immediate risk in 2014.

“The FBI had this guy. How many guys have they had that they turned loose?” Rep. David Scott (D-Ga.) said Tuesday after the briefing.

Said King: “Really the question is, should the investigation have been closed? To me, there was enough here to keep it in some sort of a status.”

Rep. Steve Cohen (D-Tenn.) said: “I think they [the FBI] should have gone further. Obviously hindsight’s 20-20, but they knew [Mateen] was lying to them on occasion, so when he’s lying, then some of the reasons why they originally got into [an investigation] become still valid.”

But part of the problem might be a legal one. When the FBI closed the case against Mateen in 2014, officials had to take him off the terrorism watch list.

That doesn’t sit well with lawmakers who think the government should be able to keep tabs on people who could pose a threat, even if they don’t have enough evidence to continue a formal investigation.

“The only way you should get off the list is if they no longer believe you’re a threat,” said Sen. Lindsey O. Graham (R-S.C.). “It should have nothing to do with not being able to prove a crime.”

Graham said Tuesday that he would be willing “to say that if you’re being investigated by the FBI because of your actions, that that’s enough to get you into a system. A separate system.”

Graham said he wasn’t sure whether that system ought to be a list, but when someone who has been investigated by the FBI tries to buy a gun, “the FBI needs to be alerted,” he said. 

At this point, congressional leaders are pursuing different strategies to respond to Orlando.

In the Senate, leaders are arguing over Feinstein’s measure to grant the attorney general the power to block sales to anyone with suspected links to terrorism, whether on an official watch list or otherwise. Democrats plan to offer the measure as an amendment to an appropriations bill this week.

Meanwhile, Senate GOP leaders maintained they are “open” to talking about responses to the Orlando attack but wanted to hear from Comey and Johnson in a Wednesday briefing.

According to an aide, Republicans are also thinking about reviving an alternative to the Feinstein bill from Sen. John Cornyn (R-Tex.) that would require probable cause to ban a suspected terrorist from purchasing a gun within 72 hours of the attempted transaction.

Both measures failed to pass the Senate in the wake of the San Bernardino, Calif., attack last December.

In the House, Democrats are also pushing for votes to restrict gun sales, such as a measure to prevent people on the no-fly list — a smaller group of people who are on the overall watch list — from purchasing firearms. While Mateen was placed on the FBI’s watch list, he was never on the no-fly list.

But House GOP leaders are taking a different tack entirely.

They are planning to assemble a package of three bills related to terrorist radicalization in the United States that have already passed the House and deliver those to the Senate on Thursday.