FRANKFURT, Germany (AP) - The suspect in the slaying of two U.S. airmen at Frankfurt airport has confessed to targeting American military members, a German security official said Thursday as investigators probed a possible act of Islamic terrorism.
German federal prosecutors took over the investigation into Wednesday's shooting, which also injured two U.S. airmen, one of them critically. They are working with U.S. authorities, who said Thursday the suspect was not on any American watch list.
A federal judge in Karlsruhe on Thursday ordered the suspect held in prison on two counts of murder and three counts of attempted murder pending further investigation. A fifth American was apparently targeted but not injured in the attack.
German federal prosecutors said "there is a suspicion that the act was motivated by Islamism."
Hesse state Interior Minister Boris Rhein told reporters in Wiesbaden that the suspect, identified as a 21-year-old ethnic Albanian from Kosovo, was apparently radicalized over the last few weeks. Relatives in northern Kosovo named him as Arid Uka and said his family has been living in Germany for 40 years.
Uka lived in a 12-story apartment building in the working-class suburb of Sossenheim -- the same building where a man with links to the Islamic Movement of Uzbekistan, Rami M., also lived, said a German official, speaking on condition of anonymity because he was not authorized to talk with the press.
Rami M., whose last name has not been released, was picked up in Pakistan last year and extradited to Germany, where he faces charges of membership in a terrorist organization. It was not clear how much contact the two had -- Rami M. left Germany in 2009 for Pakistan -- but neighbors said they had known one another.
The suspect opened fire on a U.S. Air Force bus carrying 15 airmen based in the Lakenheath airfield in eastern England from Frankfurt to Ramstein Air Base, the Air Force said. From there, the airmen were to deploy to Afghanistan.
The U.S. Air Force identified the two slain airmen as 25-year-old Senior Airman Nicholas J. Alden of South Carolina, and Airman 1st Class Zachary R. Cuddeback of Virginia.
Alden was assigned to the 48th Security Forces Squadron at RAF Lakenheath in England. Cuddeback was assigned to the 86th Vehicle Readiness Squadron at Ramstein Air Base in Germany.
Uka's family said he worked at Frankfurt airport and was a devout Muslim. He was taken into custody immediately after the shooting.
There was disagreement Thursday between German and American officials whether the suspect may have had help. So far, German investigators thought he did not, but Americans were not ruling that out.
"From our investigation so far we conclude that he acted alone," Rhein said. "So far we cannot see a network."
But Pentagon spokesman Marine Col. Dave Lapan said was still not clear whether others could have been involved in planning the attack.
"One of the key focuses of the investigation will be to determine whether others were involved in the incident besides the shooter," Lapan said.
The U.S. Air Force said one of those killed was stationed at Ramstein and was driving the bus, while the other was part of the team bound for Afghanistan.
Rhein said the suspect's apartment and computer have been searched. He said investigators believe the suspect had contact with other radical Muslims on a social network site "but there is no network in the sense of a terror cell."
"There are signs that this is about a radicalized Muslim," he said.
The suspect's Facebook photo features a silhouette of Kosovo, with the phrase "There is no God but God and Mohammad is his prophet" written above it on Arabic. Rhein said the suspect recently changed his profile name from his real name to the nom de guerre "Abu Reyyan."
One of his Facebook friends said he knew little about him.
"He was very unremarkable and low-key," Kerem Kenan wrote to The Associated Press. "We had no personal contacts. I'm appalled by the incident."
One airman remained in critical condition after being shot in the head but the other injured airman was not in a life-threatening condition, the DAPD news agency reported. None of the victims have been publicly identified, pending notification of next of kin.
At the suspect's father's home in Frankfurt, a man yelled at reporters to "go away" Thursday and threatened to call police. Neighbors described Uka as a loner who kept to himself but was never unfriendly.
"I do think he was religious, but he is just a normal young guy -- completely normal," neighbor Katharina Freier told AP Television News. "We were all shocked."
Kosovo is mostly Muslim, but its estimated 2 million ethnic Albanians are strongly pro-American due to the U.S.'s leading role in NATO's 1999 bombing of Serb forces that paved the way for Kosovo to secede from Serbia.
The U.S. Embassy in Pristina said the attack "will in no way affect the deep and abiding friendship between our two countries."
Uka's uncle, Rexhep Uka, said the suspect's grandfather was a
religious leader at a mosque in a Kosovo village near Mitrovica, and that Arid Uka was a devout Muslim himself. But he also said the family was pro-American and did not understand what their nephew was involved with.
"I love the Americans because they helped us a lot in times of trouble," he told the AP.
Behxhet Uka, a first cousin, said he had spoken to the gunman's father in Frankfurt several times, and the family told him all they knew was that their son did not come home Wednesday from work at the Frankfurt airport.
"We could not imagine something like this would happen because Americans are our brothers," he said.
Deutsche Post said the suspect was a part-time employee in an airport mailroom. Spokesman Dirk Klasen told DAPD the suspect had a clean police record.
"Otherwise we would not have hired him," Klasen said, noting the suspect's contract was to run out in a few weeks.
The U.S. has some 50,000 troops stationed in Germany. It operates several major facilities in the Frankfurt region, including the Ramstein Air Base, which is often used as a logistical hub for operations in Afghanistan and Iraq.
Eddy reported from Berlin. Juergen Baetz and David Rising in Berlin, Bassem Mroue in Cairo and Pauline Jelinek and Eileen Sullivan in Washington also contributed.
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