Tora Bora operation fails to find bin Laden

Coalition members dig in a search for the remains of al Qaeda leaders on Tuesday.

BAGRAM AIR BASE, Afghanistan (CNN) -- A Canadian-led mission to find the remains of al Qaeda leaders in the mountainous Tora Bora region of Afghanistan ended Tuesday without uncovering whether the most notorious of all -- Osama bin Laden -- is dead.

The Tora Bora region was the scene of heavy fighting and an intensive U.S. air campaign in December, and intelligence sources believed it was possible that bin Laden had been trapped in a cave destroyed by the bombing, military sources said.

The main contingent of Operation Torii -- 372 Canadians and specialists from the U.S. Army's Criminal Investigation Division, U.S. military intelligence and the FBI -- headed into the treacherous mountains 30 kilometers from Jalalabad three days ago after about 20 U.S. Special Forces had arrived for early reconnaissance.

"The primary goal of the operation was to conduct sensitive site exploitation and to conduct demolition operations in order to deny al Qaeda ability to operate in this area," said Luc Charron, a Canadian army spokesman.

Searchers failed to find the entrances to the caves despite blasting rubble away.

But military sources told CNN's Ryan Chilcote, one of a handful of journalists who traveled with the mission, that the operation's goal was to find and identify the remains of what the U.S. military calls "high value targets" -- al Qaeda leaders -- and especially to find if bin Laden was killed.

Of particular interest, the sources said, was Cave No. 4, one of four underground facility sites closed down by U.S. bombs after a remotely operated Predator surveillance aircraft spotted about 40 to 70 al Qaeda fighters running into the cave. (Caves of Afghanistan)

According to military sources, those fighters never left the cave.

Intelligence experts say they believe they intercepted bin Laden radio communications in the area in early December -- but none after the attack, leading them to believe the al Qaeda leader could have been killed.

CNN NewsPass VIDEO CNN's Ryan Chilcote shows video of a Canadian-led mission searching in the Tora Bora region of Afghanistan for the bodies of al Qaeda leaders -- hoping to find remains of Osama bin Laden. (May 7) Play video

But the troops were unable to find the cave's opening amid the mounds of rubble, even after blasting some of the rubble away. The same was true for the other three sites, which they believed were likely connected to Cave No. 4 as part of the infamous Tora Bora cave complex.

The mission had better luck at a nearby village, however, when villagers there told them they had buried about 25 Arab fighters in the village graveyard. After obtaining permission from the village elder to do so, the Canadian-led forces excavated at least 23 graves over the course of two days.

They took DNA samples from all the corpses to try to identify them. They also measured the corpses, but none came close to the estimated height, 6 foot-5-inches, of Osama bin Laden.

The troops returned on Wednesday to Bagram Air Base, the staging area for the operation, although many of the troops are based at Kandahar Air Base.

-- CNN's Ryan Chilcote contributed to this report.