The accused, Mohit and Anuj, allegedly killed Gajendra (45) for having illicit relationship with Mohit's mother on September 5 at Sikreda village in the district, Station House Officer Arun Kumar Tyagi said.
Both of them surrendered before court yesterday and was taken to police custody, he said.
Later, third accused Gaurav was picked up by the police and during interrogation he confessed that Mohit with the help of him and Anuj has strangled his mother Kamla and sister Moni to death on the same day when Gajender was shot dead, the SHO said.
Gaurav will be produced before the court today.
Mohit, son of Kamla, was against their relationship. He with the help of two other people shot dead Gajendra and dumped the body in a canal, the SHO added.