The five, all British citizens, were convicted Monday of plotting to attack the London targets with bombs made from a half-ton stockpile of fertilizer after a yearlong trial in which prosecutors and an FBI informant claimed the group was linked to al Qaeda leaders. It was Britain's longest terror case.
It was also the country's most intensive surveillance operation ever, reports CBS News correspondent Sheila MacVicar. Investigators bugged more than 90 phone lines, sifted through 27,000 hours of video and audio intercepts and logged more than 33,000 hours watching the conspirators.
Surveillance teams tracking the five men stumbled onto the transit attackers over a year before they killed 52 commuters on July 7, 2005, but officials failed to piece together intelligence in time to halt the blasts.
Though agents slipped a tracking device on transit bombing ringleader Mohammed Siddique Khan's car and heard him pledge to carry out violence against non-Muslims during bugged conversations, Britain's MI5 spy agency halted surveillance — deciding he was not a priority.
Details of ties between the plotters and the subway bombers were kept secret from the jury to ensure a fair trial. The links were revealed in closed sessions and confirmed Monday by government officials and police.
Security officers claim Khan, accomplice Shehzad Tanweer and the mastermind of the fertilizer bomb plot, Omar Khyam, trained together at camps in Pakistan and met Abdul al-Hadi al-Iraqi, an al Qaeda operative now held at the U.S. prison camp at Guantanamo Bay.
The revelations are at odds with statements by Britain's government after the 2005 attack, when senior ministers — who a month earlier had lowered the country's alert status — said the strike was unexpected and the perpetrators unknown.
Jurors deliberated for almost a month over the plot to detonate bombs made from 1,300 pounds of fertilizer stockpiled in a London storage unit.
Khyam, 25, Anthony Garcia, 25, Jawad Akbar, 23, Waheed Mahmood, 35, and Salahuddin Amin, 32, were sentenced to life in prison for conspiring to cause explosions.
Garcia, Khyam and Waheed Mahmood will be eligible for parole after 20 years, and Amin and Akbar, after 17½ years — but all five were warned they could face spending the rest of their lives in jail.
Two others, Nabeel Hussain and Shujah Mahmood, were cleared of conspiracy to cause explosions. All seven are British citizens — six with family ties to Pakistan.
Khyam, who led the fertilizer bomb plotters to militia camps in Pakistan, was steeped in radicalism. At age 16, he dropped out of school and went to Kashmir and later visited Afghanistan to meet members of the Taliban.
Khan, Tanweer, and American radical-turned-FBI informant Mohammed Junaid Babar joined his 2003 camps, prosecutors said.
In Britain, conversations on 100 bugged phone lines and at two houses were taped, capturing Khan and Khyam discussing terrorism and the fertilizer bomb plotters debating possible targets, including central London's Ministry of Sound nightclub, with a capacity for 1,800 revelers.
Tapes revealed Mahmood and Khyam proposed attacks on a British construction firm, Amec, which has contracts in Iraq and helped clean up after the Sept. 11 attacks on the World Trade Center and the Pentagon.
Mahmood, who worked for a utility supplier, suggested an attack against British electricity, water and gas power supplies.
In testimony, Babar, a naturalized American from Pakistan, said al-Iraqi had urged Khyam's group to carry out attacks in Britain.
"I have no doubt that they are clearly linked to the heart of al Qaeda," said Peter Clarke, Britain's police counterterrorism chief.
Some 700 police halted the plot in dawn raids in March 2004. Final targets had not been selected, but plans were dangerously close to execution, prosecutors said.
Khan was monitored alongside the fertilizer bomb plotters and details of his activities were reported by informants who knew him only by aliases. But he was never ranked as a major threat.
A government security official, who briefed reporters on the case in exchange for anonymity, said 15 other terror suspects were ranked as higher priorities than Khan and Tanweer.
But only one of those suspects was later jailed: Kazi Rahman — a man officials believe was trying to buy a missile launchers to target passenger jets. He pleaded guilty to possessing weapons for the purpose of terrorism.
Stretched by a growing number of suspected plots, MI5 never pieced together the intelligence on Khan. "There needs to be that killer fact and it just wasn't there," the official said.
Babar told U.S. authorities that Khan — whom he recognized from a blurred surveillance photograph — had sought meetings with al Qaeda leaders and warned he "should be checked out." But he didn't know Khan's real name and the tip was too vague to prompt action, the official said.
Intelligence on Khan and his cell was pieced together only months after their bloody attack, the official said — when their identities and aliases were established.
Prime Minister Tony Blair has ordered a panel of lawmakers to review an inquiry into the London bombings, which absolved counterterrorism officials of any blame last year.
But the government has ruled out demands from survivors and opposition lawmakers for a public inquiry based on the U.S. Commission into the Sept. 11 attacks.
"The security service will never have the capacity to investigate everyone who appears on the periphery of every operation," MI5 chief Jonathan Evans said, adding his agents would always regret failing to halt the London bombings.