The victim, identified as Pragash Ram, who fell sick in the jail, was admitted to the hospital last night and breathed his last in the wee hours today, they said.
Ram had been convicted and languishing in the jail since 2000 for murdering his wife for dowry, they added.
Deputy Commissioner of Palamau, K N Jha has ordered a probe into Ram's death and directed Medininagar Sadar sub-divisional Magistrate, Surendra Kumar Verma to submit a detail report.