Ishwer Chand Tyagi, 65 is the father of the Uttar Pradesh cadre officer Sanjeev Tyagi, was shot dead at 6.40 am by Daboo Tyagi, Senior Superintendent of Police H N Singh said.
Daboo Tyagi escaped after the incident, he added.
Ishwer Chand Tyagi, a native of Morta village of Muradnagar, lived in Rajnagar with his four sons.
Preliminary investigation reveals that Mr Daboo is suffering from schizophrenia and undergoing treatment at a hospital in Delhi.
A case has been registered against Mr Daboo on a complaint filed by his cousin Amit Tyagi.
Officer Tyagi's body has been sent for postmortem.
Three teams of Sahibabad and Kavinagar police stations and Crime Branch are on the lookout for Mr Daboo.
Officer Tyagi's orther son, Sanjeev Tyagi is posted as the SP of Cooperative Cell in Lucknow.