EXCLUSIVE: How John Mark Karr Was Caught

Aug. 18, 2006 — -- JonBenet Ramsey may be the most famous child murder victim in history. Now almost 10 years and 100 suspects later, police have made the first arrest connected with her death. How did they catch their man? The answer may lie in a 21-speed bike.

ABC News has learned that as of three weeks ago, U.S. law enforcement officials knew they might have a new suspect in the young beauty-queen's death. But they learned his identity only about a week ago.

U.S. law enforcement had been monitoring e-mails between Michael Tracey -- a journalism professor at the University of Colorado at Boulder and a producer of three documentaries on the Ramsey case -- and a man obsessed with JonBenet. The e-mails allegedly included poems to the dead little girl and empathized with Michael Jackson's relationships with children.

The e-mails also divulged details of Karr's life oversees -- mentioning people he knew, people he's met, and his teaching jobs. Officials were getting closer, but what they needed was a name and a face.

Their e-mail suspect had never been identified. And he used a pseudonym every time.

The Secret Stakeout

U.S. law enforcement officials told ABC News that a little over a week ago Tracey sent Karr another kind of mail -- a photograph delivered to a Thai post office box. Agents arranged a control delivery and were ready to spot their suspect.

How did the FBI nail Karr?

Sources told ABC News that the man who came for the mail delivery arrived on a 21-speed bicycle -- a bicycle the mysterious man from the e-mails had recently mentioned purchasing. His identity was still unknown.

They followed Karr to his residence and finally learned his name -- a name that in three short days has become infamous. John Mark Karr -- the brand-new suspect in the decade-old case.

Karr is currently detained in Thailand and is on a 24-hour suicide watch. Upon arrival in the United States, he faces charges in Boulder, Colo., in connection with the 1996 murder of JonBenet Ramsey.