Investigators have obtained an account of a tense exchange said to have taken place in the treatment room where Greek singer Giorgos Mazonakis was undergoing plasmapheresis, a procedure that separates plasma from the blood, shortly before his death at a private medical practice in Athens.

Authorities are reconstructing, minute by minute, the singer’s final moments at the practice on Karneadou Street in the upmarket Kolonaki district. The clinic, The Stem Cell Clinic, has been at the centre of the investigation into the circumstances in which the singer suffered cardiac arrest.

At the heart of the inquiry is the testimony of a 53-year-old nurse, identified only by the initials E.Th., who was giving therapeutic massages and was in the room during the procedure.

According to new information obtained by protothema.gr, the nurse saw one of the singer’s arms jerk. Alarmed, she immediately turned to Dr Ioanna Gaka. “He doesn’t look well to me,” she is alleged to have said.

The 56-year-old doctor replied, according to the testimony: “You don’t get to tell me, I’m the doctor.”

At the same time, the plasmapheresis machine was repeatedly sounding alerts, and the singer’s condition was already causing serious alarm among those present. Evidence from the clinic has indicated that the machine began operating at 14:14:10 on 9 September and ran for 42 minutes, contradicting the doctors’ own account.

Two calls over the defibrillator

What happened next is now under close scrutiny. Gaka reportedly made two phone calls to the defibrillator’s manufacturer to obtain instructions on how to use the device.

The calls were allegedly made on speakerphone, so that everyone in the practice could hear the guidance.

Gaka and her husband, Dr Ilias Theodoropoulos, have been remanded in custody. The couple were arrested by officers of the Athens Crime Investigation Sub-Directorate on a charge of exposing a person to danger resulting in death, and reports have indicated that an upgrade of the charge to homicide with possible intent is being considered.

Investigators are examining, among other things, how the machine’s alerts were handled, the steps taken after Mazonakis deteriorated and when the National Centre for Emergency Care (EKAB), Greece’s ambulance service, was called. The Health Minister has pointed out that plasmapheresis is a specialist procedure carried out only in properly equipped hospitals, not in an ordinary medical practice.

The call to an anaesthetist

Considered even more significant is a phone call made at about 4.15pm, minutes before EKAB was summoned. Lasting only a few seconds, it was placed by a woman inside the practice to an anaesthetist at a private hospital.

The anaesthetist is reportedly an external associate who is called in for emergencies.

According to the content of the conversation now before the authorities, the woman said: “I have given a patient an anaesthetic. I have also given the antidote. Is there anything else I can give in this situation?”

The call has become one of the most important strands of the investigation as detectives try to establish exactly what happened.