35-year-old Jainarayan Raut succumbed at his home last night, Additional Superintendent of Police (ASP) P K Mandal said.
An autopsy was carried out, but it failed to specify the cause of Raut's death, he said.
Nine persons, including two women, had died in Bahrupia and Phulwaria villages on Sunday following the outbreak of the mysterious disease as some villagers had cremated the body of one Rita Devi on their own without informing local police, Mandal said.
The viscera of the bodies will be kept at hospital for further investigation, she said.
Former Deputy Chief Minister and BJP leader Sushil Kumar Modi claimed that cause of death is consumption of hooch and accused the JD(U) government of suppressing facts.