The private clinic in central Athens where Greek singer Giorgos Mazonakis suffered a fatal cardiac arrest was secretly carrying out plasmapheresis at weekends and late at night, according to the Athens Medical Association (ISA).

The association’s legal adviser, Katerina Fragkaki, told ERTnews, the news channel of Greek public broadcaster ERT, that its investigation had uncovered evidence the procedure was being performed outside the clinic’s declared opening hours.

Mazonakis, 54, died on 9 September after collapsing during a plasmapheresis session, a treatment that filters and replaces blood plasma, at the Stem Cell clinic on Karneadou Street in the upmarket Kolonaki district. Health Minister Adonis Georgiadis has said the facility was licensed only as a general internal medicine practice and had no authorisation to carry out the procedure.

Fragkaki said the plasmapheresis machine appeared to have been running for about 42 minutes during the singer’s treatment. Its logs are also being examined for other sessions in the days before his death. According to Fragkaki, the data show the machine was used on days and at times when the clinic said it was closed. “On 28 August it was used in the evening, at 11.33pm, on a patient. The clinic said it was open from 9am to 9pm,” she said.

She added that the machine was switched on on Saturday 29 August, “even though they don’t operate at weekends”, and that on Sunday 30 August it “was used on a patient, as the machine’s records show”. Fragkaki said the weekend sessions took place without the association being informed or giving its approval. “They did it in secret. They did not have approval from the ISA. They knew what they were doing was illegal,” she said.

She said the clinic had been inspected in both 2025 and 2026, and that the association uncovered fresh evidence after the singer’s death. “The morning after Mazonakis died, the ISA found a great deal of evidence,” she said, alleging that “the two doctors tried to deceive the ISA”.

The two doctors who ran the clinic, Ioanna Gaka and Ilias Theodoropoulos, are in pretrial detention on charges of causing death by exposing another person to danger. Both deny any wrongdoing.

Athens Medical Association joins case against doctors over singer Mazonakis’s death

ISA has now formally joined the criminal proceedings over the death of singer Giorgos Mazonakis in support of the prosecution.

According to reports, the association handed the investigating magistrate invoices and photographs of two medical devices that Gaka had previously submitted to it.

ISA maintains that Gaka and her husband, internist Dr Ilias Theodoropoulos, illegally possessed and used both machines. It also alleges that Gaka, who is registered as a doctor without a specialty, falsely declared one of them to the association as an attachment for an ozone therapy machine. The association said it had taken the step over acts and omissions that gravely offend the medical community.