Five suspects were arrested after Turkish police discovered an organ-trafficking ring that paired Bulgarian citizens with Bulgarian donors and used a hospital in Turkey for transplant surgeries.

Bulgarian police notified their Turkish counterparts about the gang, who used a private hospital in Istanbul for illegal organ transplants facilitated with forged documents. The subsequent investigation, made public on Monday, led police to an employee at the hospital, a 55-year-old Turkish woman identified only by her initials, F.Ö. The hospital also runs a clinic in the Bulgarian capital of Sofia and F.Ö. was accused of finding recipients at this clinic and arranging their surgeries in Istanbul, pairing them with unknown donors. In line with Turkish law, an organ transplant from a donor not related to the recipient must normally be inspected by a medical board.

The suspect is accused of forging documents purporting to show recipient and donors as couples or siblings. She was arrested on Feb.1 at the hospital in Istanbul, while trying to arrange documents for another recipient and an illegal donor. Three other suspects, all Bulgarian nationals, were detained while trying to flee the country via Turkey’s border crossing with Bulgaria. F.Ö.’s husband was also detained for aiding and abetting suspects while a suspected donor was found out to have fled Turkey, evading arrest.