The death of a 42-year-old man in police custody in Assam’s Lakhimpur district on Wednesday night was due to “pre-existing” coronary disease, said police.

Assam police chief G.P. Singh said in a post on Saturday that the preliminary post-mortem reports of the person, Ashraf Ali, who died in police custody are “indicative of death due to pre-existing coronary disease”.

On Thursday, the police said Ali fell off a bench he was sitting on and was rushed to hospital, where he was declared brought dead. He was picked up along with four others in a mobile theft case. He was the “alleged receiver” of stolen goods.

“The district police superintendent has been directed to withdraw suspension orders of the policemen, including the inspector-in-charge. However, detailed inquiry and mandatory follow-up would continue,” Singh said.

Singh also said 15 persons had been arrested in connection with Thursday morning’s stone-pelting attack at Khelmati police outpost, where Ali died the previous night.

The arrested persons included two minors.

Ali is survived by his mother, wife and two daughters.

“Materials preparatory to arson have also been recovered and seized during the searches...,” Singh said.

Local residents started gathering at the police outpost from 8.30am on Thursday, protesting Ali’s death. The situation escalated by 10am, prompting the police to first resort to lathicharge and then fire tear gas to push the crowd back. However, the mob, numbering around 300, started retaliating by hurling stones forcing the cops and other commuters to flee the area. The situation was brought under control by 11am.