Police investigate at the site of the mob killing in Assam's Tinsukia.

A man and his mother were beaten to death by an angry mob in the presence of a policeman at Shewpur Tea Estate in Upper Assam's Tinsukia district on Friday. The incident came to light after a video of the murder was widely shared on social media.

Police said villagers murdered Ajay Tanti and his mother, Jamuna Tanti, over suspicions that they had killed the former's wife and their two-month-old child earlier this month. They also defended the policeman present at the scene, claiming that he was outnumbered by the mob.

Ajay Tanti's wife Radha Tanti Garh and her two-month-old daughter had gone missing on June 5, following which her family members filed a complaint. On Friday, local residents allegedly found the woman's body in a septic tank near their house. Angered, they attacked Ajay Tanti and his mother with rods and sticks. While Jamuna Tanti was killed almost immediately, Ajay Tanti died of his injuries in the district hospital on Saturday morning.

Police said they have registered two separate cases, one pertaining to the mob killing and another lodged by Radha Tanti Garh's father. The family belonged to the tea tribe community and worked in the same garden, they added.

While no arrests have been made in both cases, a search has been launched for the two-month-old infant.

The incident comes a year after two young men were killed by a mob in Assam's Karbi Anglong, triggering nationwide outrage. On June 8, 2018, a mob of around 250 people attacked two men on suspicion of child trafficking and beat them to death. Police later dubbed it as a case of mistaken identity and attributed the public reaction to the spread of false news on social media platforms as well as messaging apps such as WhatsApp.