The ruse cost him his life, according to a former Pakistani military intelligence official, Mahmood Shah. The Taleban began to suspect him, and after multiple interrogations executed him.

The case of Rahman, which Shah recounted, falls in line with a key aspect of the fight against terror — Western intelligence agencies, with help from Islamic allies, are placing moles and informants inside Al-Qaeda and the Taleban. The program seems to be bearing fruit, even as many infiltrators like Rahman are discovered and killed.

It was a tip from an Al-Qaeda militant-turned-informant that led international authorities to find explosives hidden in printer cartridges from Yemen to the United States a week ago, Yemeni security officials say. Officials say the explosives could have caused a blast as deadly as the 1988 Lockerbie bombing in Scotland that killed 270 people.

Intelligence agencies such as MI6 and the CIA have hired more agents from diverse backgrounds since the terror attacks on Sept. 11, 2001, and others that followed. Many say the tactics have worked: Several plots, also including the 2006 trans-Atlantic airline plot, were thwarted because intelligence agents were able to use tips to track the would-be terrorists.

In recent years, US, European and Pakistani intelligence officials have said Al-Qaeda has been weakened by CIA drone strikes along the Afghanistan-Pakistan border and by governments planting agents within terror cells. Top leaders have been taken out of the picture or trust has been eroded enough that militants have begun to turn on one another.

In an unprecedented public speech last week, MI6 chief John Sawers revealed for the first time that the British spy agency had managed to “get inside” terror organizations. He would not elaborate.

“Layers of Al-Qaeda’s security have been slowly worn down and it’s much easier today to infiltrate these groups,” says Noman Benotman, a former jihadist with links to Al-Qaeda in Afghanistan, Pakistan and Sudan, and now a security and terrorism analyst in London.

Saudi Arabia has had some of the most success with spies in the Arabian Peninsula, some of whom have been former Guantanamo detainees, Benotman says. Jail time at Guantanamo is a new asset on the resumes of many double agents, security officials say — an ultimate sign of credibility that often makes them revered and trusted among senior operatives.

Yemeni authorities have said a tip on last week’s mail bomb plot came from a Saudi informant who returned from Guantanamo in 2007, spent time in the rehab program and fled to Yemen before handing himself in to Saudi authorities in late September.

Although some countries have had some success using former prisoners, the results have been less successful in places such as Pakistan where Rahman was executed for being a double agent.

A second Pakistani military official, who spoke on condition he not be identified because information on informants is rarely made public, said that more than 50 infiltrators and informants have been executed by the Taleban or Al-Qaeda over the past seven years.

Afghanistan has had slightly better results using informants.

A former Afghan official said that his country has sent dozens of Afghans across the border into Pakistan’s tribal regions to infiltrate and return with intelligence. He asked not to be identified because he feared a backlash from the government, but said the program had been successful in providing intelligence for both the NATO-led forces and the Afghan government.

Moazzam Begg, a Briton who was held in Guantanamo for more than two years, said the CIA and the British spy agencies MI5 and MI6 made repeated attempts years ago to get him to become an informant. But he said he doubted many Guantanamo detainees would agree to turn for the CIA or Pakistani authorities because of the coalition forces’ role in capturing and imprisoning them. He said the tribal regions on the border have been difficult for agents to penetrate because of intense military activity on the border.

“People have become mistrustful of everyone,” Begg said.

He said many Guantanamo detainees had struggled to return to normal lives after being held so long — some were finding it difficult to navigate new technology, let alone reach out to former friends.

Analysts say other countries have also changed tactics or looked to former militant prisoners as informants.

Benotman said Algerians had destabilized terror groups by capturing top leaders and telling cell members they had been killed — all while keeping them as intelligence assets. One leader was thought to have been killed after his capture only to eventually reappear as a double-agent, said Benotman, who spent time in North Africa.

Indonesia, too, has stepped up intelligence efforts since the 2002 Bali bombings. More than 600 militants have been netted, around 20 of whom are actively working with police.

Nasir Abbas, a former Al-Qaeda-linked militant who helped train the Bali bombers, became instrumental after his 2004 prison release in helping track down and arrest several of his former comrades.

Col. Marwoto Suto, a spokesman for the Indonesian national police, said: “Our principle is to take advantage of former terrorists and hard-liners who have repented and are committed to helping authorities.” “This is not a conventional war,” said Benotman. “The only way to defeat Al-Qaeda is through better intelligence.”