The body of a 62-year-old man was recovered from the Bathinda branch of the Sirhind canal on Sunday, over the Bir Behman bridge, a week after his mother's body was fished out from the same spot.
The woman, Nirpender Kaur (85), and the son, Rupinderjit Singh (62), had been reported missing more than a week ago.
SSP Gurpreet Singh Bhullar said the victim's hands were tied behind his back and his mouth was covered with a cloth.
"Three people -- Gurmit Singh a resident of Naruana road, Jagjit Singh from Paras Ram Nagar and Surjit Singh of Ram Nagar--- have been booked," he said. The department has also released the sketches of the accused.
The three worked as carpenters and were employed at a project near the victims' house.
The motive behind the murders has not been ascertained yet as no theft has been reported. Previously, a property dispute was suspected to be behind the crime, but with the booking of three unrelated people, the theory seems to have been defeated.
The woman's body was recognised by her son-in-law Gurdip Singh Sidhu on February 9 and a missing report for the son had been registered.