An Austrian surgeon is under investigation for allegedly permitting his 13-year-old daughter to drill a hole in a patient’s skull during an operation.

The incident took place at Graz University Hospital in Styria, in southeastern Austria, following a severe forestry accident in January, Sky News reports.

The patient, a 33-year-old man, was airlifted to the hospital with critical head injuries and required emergency surgery. According to the Austrian newspaper Kronen Zeitung, the surgeon allowed his teenage daughter to assist in the procedure, even letting her drill into the patient’s skull.

Despite the operation reportedly being successful, the patient remains unable to work, and investigations by the Graz public prosecutor’s office are ongoing against the entire surgical team.

An anonymous complaint regarding the incident was lodged with the public prosecutor’s office in April, Sky reports, but it wasn’t until July that the alleged victim was informed by the police.

The surgeon and another specialist who was present during the operation have since been dismissed from the hospital. The patient initially learned about the case through media reports before authorities contacted him to confirm he was a witness in the investigation.

“You lie there. Unwilling, unconscious, and become guinea pigs. There’s probably no other way to put it… that’s not possible. You can’t do that,” said the victim’s lawyer, Peter Freiberger.