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Failed bombers leave many clues for law enforcement. (Image via Wikimedia Commons)

With the arrest last night of Faisal Shahzad in the case of the failed Times Square SUV bombing attempt on Saturday evening, we see the continuation of a trend in which bombing attempts are botched, allowing law enforcement to move in, arrest the immediately involved suspect and then hand off the investigation to the larger government efforts against terrorism.

By all accounts, this most recent bomb was an "amateurish" attempt that failed to detonate the propane tanks and gasoline canisters in the SUV. The fertilizer alongside these items is even reported not to have had an explosive level of ammonium nitrate, and as a result, this particular bombing attempt left behind a huge number of clues for law enforcement to track.

From the first New York Times article linked above, we learn that sometime on Monday, the case was handed off from New York City police to the Joint Terrorism Task force:

The authorities have been exploring whether the man or others who might have been involved in the attempted bombing had been in contact with people or groups overseas, according to federal officials.

The investigation was shifted on Monday to the control of the international terrorism branch of the Joint Terrorism Task Force, a multiagency group led by the Justice Department, according to two federal officials.

“As we move forward, we will focus on not just holding those responsible for it accountable, but also on obtaining any intelligence about terrorist organizations overseas,” Mr. Holder said.

Although we don’t know yet what clues allowed Shahzad to be identified, it seems reasonable to believe that information as basic as fingerprints could well be involved. Since we already are seeing reports Shahzad traveled recently to Pakistan (where he was born), it would make sense that once he was identified and known to have recently been in Pakistan, the case would be handed over to the Joint Terrorism Task Force for them to investigate potential ties to known terrorist groups.

Note the efficiency of this model for disrupting terrorist cells. Trying to identify potential terrorists before they strike is exceedingly difficult because of the "needle in a haystack" problem of sorting through huge databases or all communications traffic at a time when the government is asserting its right to do so without regard to the civil liberties violations those actions represent. On the other hand, once a suspect is known to be involved with a terrorism attempt, these same tools of database searching and communications monitoring become very powerful and avoid most of the privacy issues generated by prospective searching.

Fortunately, it appears that those who are recruited or who volunteer for these terrorist attacks often are quite incompetent in execution of the mission, opening up the chance for investigation of the entire group. In addition to Shahzad, note that Umar Farouk Abdulmutallab had an amount of explosive that likely could have taken down the airplane which he attacked, but he only managed to set his genitals on fire rather than generate a deadly explosion. There have been reports that Abdulmutallab is cooperating with interrogators, so whatever group he was working with likely is under intense surveillance.

Similarly, we still don’t know if Najibullah Zazi ever succeeded in synthesizing the explosive TATP, but with his arrest and the arrest of several of his accomplices, investigations into a wider group continue.

Finally, it is worth recalling that after the 1993 World Trade Center bombing, one of the key steps in identifying the group responsible was the arrest of one of the bombers when he tried to get a refund of the deposit on the rental truck which had been used in the bombing.

I am encouraged that the system seems to be working very well in these most recent cases. Despite the wailing of some folks that due process shouldn’t be observed (see here for John McCain telling us what a mistake it would be if Shahzad was Mirandized), letting law enforcement carry out the initial investigation of criminal acts and then hand off cases that turn out to point toward terrorism is nothing more than using law enforcement and counter-terrorism task forces exactly as they were designed to function. Throwing in massive eavesdropping or database mining without probable cause or torture in interrogation only generates far too much false information that wastes the time of a finite pool of investigators. Focusing on known terrorists and working to dismantle their wider group is a guaranteed success. Even in the extremely rare instances of successful attacks, tracing back to the group involved through careful criminal investigation in the early phases makes for a better case to hand over to the Joint Terrorism Task Force.

Oh, and one more point. Be sure to note in the quote above that the Joint Terrorism Task Force is led by the Department of Justice. So even the continued investigation into larger groups is a law enforcement function, just as it should be.