Arup Kalita went missing almost a year ago from near a forest office 50km southwest of Guwahati.
The police fished out his skeletal remains on Tuesday from a pond near that office, and they have reasons to suspect he was murdered by forest officials in league with a gang smuggling timber and forest produce such as sand.
Kalita, 28, was the secretary of the All Assam Non-Tribal Students's Union (Aantsu).
He had along with union member Dhiren Mali gone to the forest depot office at Kukurmara in Kamrup district to complain about the timber and sand smuggling gang.
Forest officials and some miscreants allegedly pounced on them. Mali escaped but Kalita remained untraced since.
Members of Kalita's family lodged an FIR at the Chhaygaon police station nearby, but the police allegedly showed disinterest in the case. They acted on Tuesday only after the Gauhati high court, on the basis of a writ petition, ordered them to locate his body.
"The police recovered the skeletal remains of a human body, and we suspect it to be that of Arup Kalita. We can however ascertain it only after carrying out a DNA test," said Kamrup district deputy commissioner SK Roy.
"Our suspicion follows the recovery of two mobile handsets, a driving license, motorcycle keys and a pair of trousers that his family members claimed belonged to him."
Aantsu president Pradip Saloi said Kalita was murdered by some forest personnel in connivance with criminals involved in illegal timber felling and removal of sand and pebbles in South Kamrup forest division.
"We demand all those responsible for his death be brought to book," he said.
Residents of the area, also seeking action against Kalita's murderers, blocked NH37 and attacked the Kukurmara forest office, whose staff had disappeared soon after the search for the body began.
Police resorted to cane-charge and tear-gas to disperse the mob.
The forest depot office is under the jurisdiction of South Kamrup Division headed by a divisional forest officer whose headquarter is at Bamunigaon 10km away.
"But the DFO who was posted here last year used to operate from this depot office," Saloi alleged.