The Latest on the bomb and gun attack that killed 44 people at Istanbul's Ataturk Airport (all times local):

12:55 p.m.

A U.S. congressman says a Chechen extremist organized the suicide bombing at Istanbul's Ataturk Airport that killed 44 people and wounded hundreds of others.

U.S. Rep. Michael McCaul, chairman of the House Committee on Homeland Security, tells CNN that Akhmed Chatayev directed the Tuesday night attack.

Turkish and Swedish media have also identified Chatayev as the organizer, although Turkish authorities have not confirmed his involvement. McCaul says Chatayev's whereabouts are unclear but he is known to have served as a top lieutenant in the Islamic State's war ministry. Turkish authorities have blamed the attack on the Islamic State group, though the group has not claimed credit.

Authorities have said the three suicide bombers in the attack were from Russia and the Central Asian nations of Uzbekistan and Kyrgyzstan, but they have not provided more details or said whether they are searching for more suspects.

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9:55 a.m.

As Turkey continues to investigate the Istanbul airport bombing and track down suspects, a Turkish official says the mastermind of an earlier suicide bombing has been killed.

The official said Friday Mehmet Sirin Kaya was killed by security forces in the town of Lice in the mainly Kurdish province of Diyarbakir.

The Feb. 17 suicide attack against military personnel in Ankara killed 29 people and was claimed by an offshoot of the Kurdistan Worker's Party, or PKK, which Turkey considers a terrorist organization.

The official spoke on condition of anonymity in line with government protocol.

Turkey is still reeling from the triple suicide bombing attack at Istanbul's Ataturk Airport earlier this week that killed 44 people. The Islamic State group is the main suspect for that attack.