Peshawar , Pakistan ( CNN ) A former lawyer for the doctor who helped the CIA look for Osama bin Laden has been shot dead in northwest Pakistan , police said . Unidentified gunmen attacked the lawyer , Samiullah Afridi , in his car near the city of Peshawar on Tuesday , said Mian Saeed , a police superintendent in Peshawar . Two different militant groups claimed responsibility for the killing . The lawyer had represented Dr. Shakeel Afridi , who was convicted of treason in 2012 by a Pakistani tribal court and is now serving a 23-year prison sentence . The two men are not related . The doctor helped the CIA set up a fake vaccination campaign in an attempt to collect DNA samples from relatives of Bin Laden in an effort to verify his presence in a compound in the Pakistani city of Abbottabad . The Qaeda leader was killed in a U.S. raid on the compound in May 2011 . It was unclear which of the two groups claiming responsibility for the attack was actually behind it . Fahad Marwat , a spokesman for the militant group Jundallah , told CNN that Afridi was on the group 's hit list . But Ehsanullah Ehsan , a spokesman for a faction of the Pakistani Taliban , said his group had carried out the assassination because Samiullah Afridi defended the doctor , whom he described as `` a friend '' of bin Laden 's killers . CNN national security analyst Peter Bergen said Jundallah is `` kind of a splinter group '' of the Pakistani Taliban that 's `` been around for a long time . '' `` They 're extremely violent , '' he said . `` They 've been killing all sorts of religious minorities in Pakistan . '' Last month , the group claimed responsibility for a suicide bombing outside a Shiite mosque in the city of Rawalpindi . Bergen said Dr. Afridi is `` a very unpopular figure in Pakistan '' because of the perception that he was involved in helping find Bin Laden . `` And his lawyer , by extension , would also be seen as an unpopular person because of that perception , '' he said . But Bergen said he did n't think the doctor played a key role in the hunt for Bin Laden . `` The idea was the doctor and his staff would take DNA samples from the Bin Laden kids as part of this 'vaccination program , ' '' he said . `` That never happened because the kids never came out . '' Although Dr. Afridi was working for U.S. intelligence , `` the CIA was n't telling the doctor , you 're helping us find bin Laden , '' Bergen said . After the killing of bin Laden , health workers administering polio vaccinations have come to be viewed with suspicion by many Pakistanis . The vaccination teams have repeatedly been targeted by militants . The latest instance came Wednesday when unidentified attackers killed one polio vaccination worker and wounded another in Bajaur agency in northwestern Pakistan , local authorities said . Journalist Zahir Shah reported from Peshawar , and CNN 's Jethro Mullen wrote from Hong Kong . CNN 's Sophia Saifi and journalist Saleem Mehsud contributed to this report .
A second militant group claims responsibility for the killing . The attack comes as ISIS is fighting to hold territory in Iraq and Syria after losing ground there last year.