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MAINZ, Germany — A suspect in the death of American nanny Lauren Mann has been arrested at a Swiss refugee center, officials told NBC News on Monday.

Lauren Mann. via Facebook

Mann, a 25-year-old originally from Colorado, was found half naked in apartment in the Austrian city of Vienna last month. An autopsy showed she died from suffocation and officials said a "considerable" amount of blood was found at the scene.

A spokesperson for the Swiss Federal Ministry of Justice told NBC News that a man from the Gambia was arrested Thursday at a refugee center in the town of Kreuzlingen, around 20 miles from the Austrian border.

The suspect declined an immediate extradition request from Austria, which now has 18 days to submit an official extradition request under European Union regulations.

Neither Swiss nor the Austrian authorities would identify the suspect to NBC News.

Austria’s Kronen Zeitung newspaper said the suspect's DNA was found at the crime scene and that Austrian Federal Police tracked him down by locating his mobile phone in Switzerland.

U.S. officials are assisting with the investigation into Mann's death. She had been living in Vienna for several years and working as an au pair while studying.