A case that has cast light on Greece’s lucrative anti-aging industry took a dramatic turn Thursday when two doctors were arrested on charges of fatal exposure in connection with the death of popular singer Giorgos Mazonakis.

The death has drawn attention to an unregulated market of “rejuvenation” treatments, including unproven stem cell therapies and plasmapheresis, often performed in unlicensed private offices favored for discretion by recognizable clients. Separate cases involve unauthorized botox imports and black-market testosterone sales. One hematology professor said such clinics let “some people get rich in a short period of time.” Treatments can cost between €6,000 and €10,000, with intravenous “hangover” solutions sold for €500. The head of EOF, Greece’s medicines agency, said citizens should “trust the regulatory authorities” and only medicines that have received official approval.

The arrests of the Kolonaki clinic’s two owners came after police raided the practice, uncovering evidence that authorities say contradicts the doctors’ initial statements. The pair were taken in handcuffs to the Kypseli police station.

Investigators say the doctors changed their accounts under questioning. The clinic’s doctor first told police Mazonakis arrived around 4 pm on Wednesday. But security camera footage from the building’s entrance shows he arrived two and a half hours earlier, at 1.30 pm.