Jordanian rebel Abu Musab al-Zarqawi -- Iraq's most wanted fugitive -- recently eluded capture by American troops, but left behind a treasure trove of information, a senior military official told ABC News.
On Feb. 20, the alleged terror mastermind was heading to a secret meeting in Ramadi, just west of Fallujah, where he used to base his operations, the official said.
Task Force 626 -- the covert American military unit charged with finding Zarqawi -- had troops in place to grab the fugitive, and mobile vehicle checkpoints had been established around the city's perimeter. Another U.S. official said predator drones were also in flight, tracking movements in and around the city.
A source who had been inside the Zarqawi network alerted the task force to the meeting. Officials deem the source "extremely credible."
The senior military official said that just before the meeting was scheduled, a car was pulled over as it approached a checkpoint.
"Zarqawi always has someone check the waters," said the official.
A pickup truck about a half-mile behind the car then quickly turned around and headed in the opposite direction. Officials now believe Zarqawi was in the fleeing truck. U.S. teams began a chase, but when the truck was pulled over several miles later, Zarqawi was not inside.
What the task force did find in the vehicle confirmed suspicions that Zarqawi had just escaped. The official said Zarqawi's computer and 80,000 euros (about $104,000 U.S.) were discovered in the truck.
Finding the computer, said the official, "was a seminal event." It had "a very big hard drive," the official said, and recent pictures of Zarqawi. The official said Zarqawi's driver and a bodyguard were taken into custody.
The senior military official said that they have since learned Zarqawi jumped out of the vehicle when it passed beneath an overpass, presumably to avoid detection from the air, and hid there before running to a safe house in Ramadi.
Lt. Gen. John Vines -- the commander responsible for daily military operations in Iraq -- would not provide any detail about the apparent escape in a recent interview in Baghdad, but he did say the Zarqawi network has been damaged.
"We believe he is resilient," Vines said. "He is incredibly evil and we can't forget that. So he is dangerous still, but he is on the run."
The official told ABC News they have since figured out which house Zarqawi ran to after his escape, and the owner has been arrested. But, the official said, every time they capture one of his supporters, Zarqawi recruits someone new.
ABC News' Martha Raddatz filed this report for "World News Tonight."