Singapore's police said Thursday they were investigating the "unnatural death" of a young American woman who headed a company dealing in the Bitcoin virtual currency. Autumn Radtke, chief executive of Singapore-based Bitcoin exchange company First Meta, was found dead in her apartment in the city-state last month. A local technology website reported she had committed suicide, but later updated its report to say it was "unclear" how she died. The Singapore Police Force said they received a call on the morning of February 26 requesting assistance at a highrise residential building. "Upon police's arrival, a woman in her 20s was found lying motionless at the said location," a police statement said. "She was pronounced dead at scene by paramedics. Police areinvestigating the unnatural death," the statement said. A source, who asked not to be named, confirmed to AFP that Radtke was a US citizen. Media reports said she was 28 years old. News of Radtke's death first surfaced in the technology startup community, which has a thriving presence in Singapore. First Meta announced Radtke's death on its website but did not give a cause. "The First Meta team is shocked and saddened by the tragic loss of our friend and CEO Autumn Radtke," the company said in a brief statement. "Our deepest condolences go out to her family, friends and loved ones. Autumn was an inspiration to all of us and she will be sorely missed," the statement said, without giving details. First Meta provides a web-based exchange for users to buy, sell and trade virtual currencies for real money. Radtke moved to Singapore in 2012, and her death comes amid controversy surrounding the Bitcoin virtual currency. On February 28, Japan-based MtGox Bitcoin exchange filed for bankruptcy protection, with its chief executive saying it had lost the equivalent of nearly half a billion dollars in a possible theft. On Tuesday, Canada-based Flexcoin was forced to shut down, saying that someone attacked its systems and stole nearly $600,000 worth of Bitcoin. First Meta last year secured funding of Sg$588,000 ($464,000) from Silicon Valley-based technology firm Plug and Play Tech Center. Singapore's central bank, the Monetary Authority of Singapore (MAS), has said however that virtual currencies are not legal tender and those who deal in them should be aware of the risks. "MAS does not regulate Bitcoin, including its purchase, sale or use, whether online or via other means such as physical vending machines," MAS said in a statement last week. "Businesses and individuals who choose to accept virtual currencies in exchange for goods and services or to transact in them should be cognizant of the risks and nature of virtual currencies."