Patna, Aug 9 : Patna Police on Wednesday arrested an accused for killing his son in a village which falls under Bhagwanpur police station. The deceased son has been identified as 14 year-old Ankit Kumar. The accused father hanged him from a mango tree on July 19. After murdering his son, the father had lodged an FIR against unknown persons for killing his son. During the investigation it appeared that the accused forcibly established sexual relations with his eldest daughter and the victim saw them in objectionable position. Following the incident, the son objected to his father's act and in the fit of rage the father strangled his own son. After committing the crime, the accused hanged him from a mango tree using a Sari. 'The father was the prime suspect from day one. We have cross checked his statement with other family members and found some contradictions. When we strongly quizzed him, he broke down and confessed to his crime,' police said. Police said that the accused is also a drug and liquor addict. He was raping his own daughter for the last two-years. His wife is also mentally unstable. /IANS