-LRB- CNN -RRB- -- The man identified as the double agent who killed eight people at a U.S. base in Afghanistan was a Jordanian doctor recruited as a counterterrorism intelligence source , a senior Jordanian official said Tuesday . A former U.S. intelligence official identified the suicide bomber Monday as Humam Khalil Abu-Mulal al-Balawi . The Jordanian official , speaking on condition of anonymity , said authorities in Jordan arrested al-Balawi more than a year ago `` for some suspicious information related to him '' but released him because of a lack of evidence . `` After few months , he got in touch with us through the Internet and sent us several e-mails that include very important and rather dangerous information that might affect the security and stability of the country , '' the official said . `` We kept in touch with him through e-mails in order to get more information and also trying to bring him over to be able to get more information . We shared and exchanged the information he gave us with some other friendly countries that are involved in countering terrorism . '' The official said Jordan could not confirm that al-Balawi was the bomber , `` because we are not on the ground . '' `` But we are not denying that if he is the one , then he is the Jordanian doctor , '' the official said . The December 30 blast at a U.S. base in Khost , in southeastern Afghanistan , killed seven CIA operatives including two from private security firm Xe , formerly known as Blackwater . The eighth victim was Jordanian Army Capt. Sharif Ali bin Zeid , a cousin of Jordan 's King Abdullah II . U.S. sources said bin Zeid was the Jordanian operative working closely with al-Balawi , who was from the same hometown as the onetime leader of al Qaeda in Iraq , Abu Musab al-Zarqawi . Jordanian and U.S. intelligence agencies apparently believed that al-Balawi had been rehabilitated from his extremist views and were using him to hunt Ayman al-Zawahiri , al Qaeda 's No. 2 figure , the former intelligence official said . In a posting on its Web site last week , the Taliban in Afghanistan claimed that the bomber was an Afghan National Army soldier . On Sunday , however , Pakistani Taliban chief Hakimullah Mehsud said in an e-mail that his arm of the Islamic movement carried out the attack , using a Jordanian national . Mehsud 's message predicted , `` This will be admitted by the CIA and the Jordanian government . '' The attack was `` a huge blow , symbolically and tactically , '' because it eliminated such a large number of CIA officers , who can require years to become ingrained in the region , said Reva Bhalla , director of analysis for the international intelligence firm STRATFOR . In addition , the attack showed the ability of the Taliban to penetrate perhaps the most difficult of targets : a CIA base , she said . Former CIA official Robert Richer called it the greatest loss of life for the agency since the 1983 bombing of the U.S. Embassy in Beirut , Lebanon , which killed eight agents . An American intelligence official vowed last week that the United States would avenge the attack .