Why Some Terrorist Attacks Go Unsolved

And the clues they offer for catching whoever is behind the Boston Marathon bombing.

FBI crime scene investigators stand near an evidence marker on Boylston Street just past Berkeley Street as they sweep up towards the bomb scene of the Boston Marathon.
FBI investigators stand near an evidence marker as they sweep up toward the bomb scene of the Boston Marathon

Photo by Darren McCollester/Getty Images

Law enforcement authorities have identified “clear video images of two suspects” in the Boston Marathon bombing, according to the Boston Globe. The New York Times reports that one of the suspects, a man, may be dropping a black bag near one of the blasts. If these reports hold up—unlike the tangled mess of mistaken reporting of an arrest on Wednesday—the authorities will be a step closer to making good on President Obama’s promise that “We will find whoever harmed our citizens, and we will bring them to justice.”

The president is sending the right message of determination, and he has a reassuring track record to back him: In the last few decades, most terrorism cases in the United States have been solved. This can of course take an enormous amount of work and skill (as well as some luck). And sometimes, it also takes years. Maybe the investigation into the Boston bombing will move more quickly. But if it proves harder to crack, what clues do bombings and other terrorist crimes that have gone unsolved offer for this one?

One of the worst of these crimes is the bombing in the baggage claim of La Guardia Airport in December 1975, which killed 11 people and wounded 75. No one took responsibility. No one was arrested. “It remains unsolved and almost forgotten—except by those whose loved ones were killed or maimed,” a former New York police supervisor told the New York Times in 2008. One suspect, Croatian independence fighter Zvonko Busic, went to prison for hijacking a TWA jet and planting a bomb that didn’t go off in Grand Central Terminal. But he always said he knew nothing about the La Guardia bombing, and it remains a mystery.

There is also the botched investigation of the 1992 and 1994 Buenos Aires bomb attacks against the Israeli Embassy and a Jewish community building, which together killed 115 people. That may be the Argentine government’s fault: After getting international arrest warrants for six people—including the Iranian defense minister—and accusing Hezbollah of being behind the attack, and Iran of financing it, Argentina—incredibly—agreed to a nonbinding “truth commission” with Iran. Blech.

But in this country, since 9/11, investigations have become more advanced and more coordinated, with sophisticated forensic techniques and a wide network of informants. Because terrorism is a performative act, the bombers often send up alerts, on purpose or by accident. Video feeds have proved hugely useful in other cases, like the 2008 late-night bombing of a San Diego courthouse, where surveillance cameras caught the guy who lit the bomb in the backpack. That one wasn’t terrorism: It turned out the bomber had a kooky plan to collect reward money for calling in information about the crime. When a bombing is not a terrorist act, the culprit may be less theatrical and more elusive. In 2003, a pipe bomb went off in the main hallway of Yale Law School, and the FBI never caught anyone. (I remember this one well because my then 3-year-old son was in day care in another corner of the building. No one was injured, but for a panicky moment there, it was terrifying.)

RAND terrorism expert Brian Michael Jenkins says that historically terrorist groups have claimed credit for 50 percent of terrorism acts worldwide. In another 25 percent of cases, he says, it was easy for investigators to identify the perpetrators. (For example, Shining Path in Peru didn’t have to claim all its attacks—everyone knew.) It’s the last 25 percent that have proved harder to solve. (The stats end at about the year 2000: RAND hasn’t kept up its database since then.) When no one claims credit for a bombing, it makes the crime eerier, but it isn’t necessarily a deciding factor in catching the culprit. “Keep in mind that no claim of responsibility was made for the 1993 World Trade Center bombing, the 1995 bombing of the federal building in Oklahoma City, the 1996 Centennial Park bombing in Atlanta, or the 2010 attempted bombing in Times Square,” Jenkins wrote in an email. “In each case, suspects were eventually identified and successfully prosecuted: jihadists in the 1993 and 2010 cases and rightwing extremists in the 1995 and 1996 cases.”

That’s good news. But the investigation of the bombing of the Atlanta Olympics is, of course, also a cautionary tale. The initial suspect, Richard Jewell, turned out to be innocent. He was the one, who while working as a temporary guard, saw the backpack that had the bomb in it, alerted police, and began clearing people from the area. But he became a suspect, with all the glare of the media spotlight, and it took months for the police to clear him. The real culprit, Eric Rudolph, was only arrested years later, in 2003, after he bombed a gay night club and several abortion clinics. “He was eventually traced based on the forensics of those other bombs,” says Bruce Hoffman, director of the Center for Security Studies at Georgetown University.

Rudolph was a classic lone wolf: The independent operator who has no connection to the terrorist groups the FBI and other agencies monitor. If Rudolph had only bombed Atlanta, would he have gotten away with it? It seems likely.

Then there’s the anthrax killer, whose deadly letters killed five people in 2001. The FBI wanted to try Army scientist Bruce Ivins for the crimes, but while the agency was preparing the case, he committed suicide in 2008. The FBI put out a 92-page summary of the evidence against Ivins two years later, but his guilt is still strongly disputed. And if he didn’t send the anthrax-laced letters, then we don’t know who did. This is either the one that got away, or it’s not.

Four lessons here that are relevant to the current investigation:

  1. It’s easier to catch bombers who already have profiles in the groups counterterrorism agencies monitor
  2. The terrorist impulse toward theater and symbolism is an Achilles heel—by choosing the Boston Marathon, this bomber may have ensured that he’ll be caught on film or on camera.
  3. Lone wolves are often harder to find than cell members, but that doesn’t mean we don’t get them in the end
  4. We’ve gotten much better at the hunt, but sometimes it’s still important to slow down to get it right.

Read more on Slate about the Boston Marathon bombing.