American scientist Suzanne Eaton died of asphyxiation in Greece, authorities say

An American scientist whose body was found in an abandoned World War II bunker in Greece died from asphyxiation, according to local authorities.

Molecular biologist Suzanne Eaton, 59, was visiting the Greek island of Crete for a conference when she vanished on July 2.

Eaton's death is being investigated as a criminal act, Crete Police spokesperson Eleni Papathanassiou told ABC News.

Greek police did not release any additional details.

Eaton's body was found in northwest Crete, about 7 miles from where she had been staying on the island, Vangelis Zacharioudakis, who led the search effort by the Hellenic Rescue Team, told ABC News on Tuesday.

Family and friends believe Eaton went for a run before she disappeared. Her colleagues described her as an avid runner, and her running shoes were the only items missing from her hotel room.

The World War II bunker is in an area where many tourist stay, said Konstantinos Beblidakis, the vice mayor of the local Platanias municipality, in a statement on Tuesday.

"There are many people going out there and especially tourists who go either by hiking or to go to the villas where they have rented rooms," Beblidakis said. "It is an amphitheatrical area where many tourists pass by daily."

Eaton was a U.S. citizen and a research group leader at the Max Planck Institute of Molecular Cell Biology and Genetics in Dresden, Germany.

Her colleagues described her as a "remarkable person" whose untimely death was "devastating."

"We have lost an immensely renowned scientist and a truly outstanding human being," Hans Muller-Steinhagen, rector of the TU Dresden, said in a statement Tuesday.

The Oakland, California, native is survived by her husband and two sons.

ABC News' Ben Gittleson, Patrick Reevell and Morgan Winsor contributed to this report.