A 54-year-old foreign national, in custody at the central prison for the premeditated murder of his 34-year-old partner, died in hospital late on Wednesday night.
The justice ministry said the man had been in Nicosia general hospital over the past few days recovering from surgery.
The central prison administration has expressed its condolences to the family of the deceased.
The man was being held at the central prison for the stabbing his partner, Eirin Papakitsa, to death at her home.
Police officers discovered the woman lifeless inside the home, alongside her injured 14-year-old son and her partner.
The son told the police that he had entered the room after hearing screaming and saw the man stabbing his mother with a knife, before stabbing himself. According to the police, the boy was probably injured while attempting to save his mother.
Click here to change your cookie preferences