TAIF — Authorities have arrested a young man for beheading his parents on Sunday in an incident that has shaken the nation. The gruesome incident took place in Taif city's Al-Suhaili neighborhood. The man, using a knife, had decapitated his parents — 59 year-old father and 48-year-old mother — after confining them inside a room in their home. So far the motive behind the ghastly killing is not clear. The gruesome incident came to light when another son of the murdered couple who lived outside Taif called his parents. When he received no response, he called his parents' neighbor and requested him to check if everything was fine. When the neighbor went over to the parents' house, he was shocked to see their slaughtered bodies. The bodies were lying on the floor of the living room. He even saw the murderer cutting the body of his parents with a knife and decapitating them. "The neighbor called the police. The police came to the scene and saw the murderer wearing black clothes with his hands covered in blood. The murderer was unable to speak and it was apparent that he suffered from mental illnesses," said a source. The source said that the murderer was previously admitted to a mental hospital a year ago. He was then released from the hospital and left to live with his parents. "The father filed a disobedience lawsuit against the murderer last year. The murderer was put in prison for a year. After the murderer was released from prison, he went home to murder his parents," said the source. Makkah Police spokesman Col. Ati Al-Qurashi said the police suspect that the murderer was also drunk or was on drugs.