Islamabad , Pakistan ( CNN ) -- Al Qaeda leader Ayman al-Zawahiri has claimed responsibility for the capture in August of a 70-year-old U.S. citizen in Pakistan , according to a number of radical websites known for carrying militants ' messages . In the eighth episode of a series called `` A Message of hope and glad tidings to our people in Egypt , '' the speaker sent a `` message of support and encouragement '' to members of al Qaeda and the Taliban as well as to `` our female oppressed prisoners . '' `` We did not forget you and we will not forget you , God willing , and therefore in order to release you , we have been successful , thanks to God almighty , to capture an American Jew called Warren Weinstein , '' he said . He described the captive as `` a former employee and a current contractor working with the U.S. government in its aid program to Pakistan , which aims to fight the jihad in Pakistan and Afghanistan , and just like the Americans arrest any suspect linked to al Qaeda and the Taliban , even if they were far related . '' The speaker then listed eight demands that he said , if met , would result in Weinstein 's release . They included the lifting of the blockade on movement of people and trade between Egypt and Gaza ; an end to bombing by the United States and its allies in Pakistan , Afghanistan , Yemen , Somalia and Gaza ; the release of anyone arrested on charges of belonging to al Qaeda and the Taliban ; the release of all prisoners in Guantanamo and American secret prisons and the closure of Guantanamo and the other prisons ; the release of terrorists convicted in the 1993 bombing of the World Trade Center ; and the release of relatives of Osama bin Laden , the founder of al Qaeda who was killed in May in Pakistan . `` Your government is torturing our prisoners , and we have never tortured your prisoner , '' he added . `` Your government signed the Geneva Conventions , and then threw it in the rubbish bin , and even though we did not sign the Geneva Conventions , we are honoring your prisoner . '' The speaker said Weinstein 's fate lies with U.S. President Barack Obama . `` I warn you of Obama 's lies and deceit because he hopes that this man gets killed so he does n't have to worry about his problem . Obama is a liar . He lies , lies and will lie . He may say to you , ' I sought the release of your relative but al Qaeda got stubborn , ' so do not believe him . And he may say to you , ' I tried to contact them , but they did not answer , ' so do not believe him . He may tell you , ' I do everything in my power to release your relative , ' but again do not believe him . '' He urged Weinstein 's relatives to pressure Obama to accede to his demands `` if you want to bring back your relative . '' A U.S. official said the circumstances surrounding Weinstein 's disappearance have been murky , but added , `` It 's entirely possible that al Qaeda or one of its militant allies may be holding Mr. Weinstein and the statement by Zawahiri supports this conclusion . '' The official said that , based on the materials found in the raid on Osama bin Laden 's compound , al Qaeda 's involvement with a kidnapping would not be surprising . `` The documents from bin Laden 's hideout show his frustrated deputies were considering kidnapping and other criminal enterprises as a means of striking from their weakened state , '' said the official , pointing to the terrorist groups ' failure to conduct big attacks against Western targets . Reached Thursday at her home in Rockville , Maryland , Weinstein 's wife , Elaine , said , `` I just found out myself two minutes ago when somebody told me . I have nothing to add and no information for you . '' Weinstein was abducted from his home in Lahore on August 13 . As his three security guards prepared for the meal before the Ramadan fast , three men knocked at the front gate and offered food for the meal -- a traditional practice among Muslims during the holy month of Ramadan , Lahore police said . Once the gate was opened , the three men forced their way in , while five others entered the house from the back , tied up the guards and duct-taped their mouths , according to police . They pistol-whipped the driver and forced him to take them to Weinstein 's room , where they hit Weinstein on the head with a pistol and forced him out of the house and into a waiting car , police said . A police official said August 23 that three suspects had been arrested in Weinstein 's kidnapping . Weinstein works for J.E . Austin Associates Inc. , a consulting firm based in Arlington , Virginia . He is a development expert , according to the company 's website . The company did not immediately respond to a call and an e-mail seeking reaction . CNN 's Eric Fiegel , Pam Benson and Saad Abedine contributed to this story .
NEW : Al Qaeda 's involvement with a kidnapping would not be surprising , U.S. official says . Warren Weinstein is a former U.S. Agency for International Development worker . The 70-year-old was abducted August 13 from his home in Lahore , police said .