Gonzalo Montoya Jiménez, was found unconscious in his cell at a jail in Asturias, northern Spain,on Sunday morning, according to local newspaper, La Voz de Asturias.
Doctors pronounced him dead quickly after he was discovered and showed no signs of life.
Mr Jiménez’s body was then taken to the mortuary at the Institute of Legal Medicine in Oviedo.
Doctors informed Mr Jiménez’s family of his death and began to prepare his body for autopsy.
But before the procedure could go ahead, the prisoner began to show signs of life.
The forensics team quickly transferred Mr Jiménez to an ICU in a nearby hospital.
Mr Jiménez regained consciousness and eventually was able to talk and asked for his wife, who had been allowed to visit him in hospital.
Despite his brain being deprived of oxygen during the ordeal, doctors say that the fact that he is able to speak and remember things are good signs.
According to reports by Informativos Telecinco, it is believed that Mr Jiménez’s collapse could have been caused by catalepsy.
Catalepsy symptoms include: rigidity, unresponsiveness, and loss of muscle control, as well as slowing of vital bodily functions which could make it look like someone suffering from it was dead.
La Voz de Asturias reported that Mr Jiménez suffers from epilepsy of which catalepsy is a symptom.
Mr Jiménez is now under observation in intensive care at the Central University Hospital of Asturias (HUCA), Oviedo.
