MAINZ, Germany - An American nanny whose half-naked body was found in her Vienna apartment died of "suffocation," police in Austria said Thursday.
Lauren Mann, 25, was found at her home in the city Tuesday night.
Police are still treating the case as homicide "because third party involvement cannot be excluded," a spokesman told NBC News.
A "considerable" amount of blood was found at the scene though an initial autopsy failed to determine cause of death.
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A final autopsy showed that she died of "suffocation," police said Thursday, adding that the case has been handed to the Vienna prosecutor's office.
A spokesperson for the prosecutor's office would only say that the "investigation is ongoing and we will need to wait for results."
American authorities are assisting in the investigation, according to the U.S. State Department.
Toxicology testing has been ordered, though final results "could take up to a couple of weeks," police spokesman Thomas Keiblinger told NBC News.
He said "no specific suspect" was being investigated, adding that police have been speaking to Mann's neighbors and friends.
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She had been living in Vienna for several years, working as an au pair while studying.
She grew up in the small Colorado town of Paonia and graduated from the University Of Colorado-Boulder in 2012, according to NBC station KKCO.
Paonia resident Lisa Heinritz said Mann had taken dance lessons with her daughter as a child.
"She always seemed like a really happy little girl and had a lot of friends," Heinritz told KKCO.