Serbia's war crimes prosecutors plan to seek the extradition of an American who allegedly served in a Nazi unit that killed 17,000 civilians here during World War II. Vladimir Vukcevic, Serbia's chief war crimes prosecutor, told The Associated Press on Thursday that his investigators have been gathering information about Peter Egner, 86, a native of Yugoslavia now living in the United States, in order to try him in Serbia. "In the next few days, a formal investigation will be launched," Vukcevic said. "And absolutely, we will ask for his extradition. That goes to prove that war crimes never fall under the statute of limitations." Last month, the US Justice Department asked a federal court to revoke Egner's American citizenship, saying he had served as a guard and interpreter with the Nazi-controlled Security Police and Security Service in Belgrade from April 1941 to September 1943. Egner, who lives in a retirement community in the Seattle area, can only be extradited to Serbia if he is stripped of his US citizenship. In its complaint filed in US District Court in Seattle, the Justice Department said Egner had failed to divulge that information when he applied for US citizenship. Instead, he reported serving in a German unit and was granted US citizenship in 1966. The US Justice Department, citing Nazi documents, said that in the fall of 1941, Egner's unit executed 11,164 people - mostly Serbian Jewish men, suspected communists and Gypsies. In early 1942, it also killed 6,280 Serbian Jewish women and children who had been prisoners at a concentration camp in Belgrade. Over a period of two months the women and children were allegedly taken from the camp and forced into a specially designed van where they were gassed with carbon monoxide.