The 'D' voter identified as Basudev Biswash (58) was rushed to Kanaklata Civil Hospital on Saturday where he was declared dead, the jail authorities said here Sunday.
'D' voter is a category of voters in Assam who are disenfranchised by the government on account of their alleged lack of proper citizenship credentials.
According to Sonitpur Superintendent of Police Kumar Sanjit Krishnan, Biswash had been lodged in the detention camp since 2016.
Biswash was suffering from asthma and undergoing treatment for his medical condition, Krishnan said.
He had earlier been taken to the Gauhati Medical College Hospital for medical care.
Bishwash's body has been sent to Rupahi in neighbouring Nagaon district from where he hailed, the SP said.
The 'D' voters are determined by special tribunals under the Foreigners Act, and the person declared as a 'D' voter is not given an elector's photo identity card.
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