A local leader of Awami League, who was in Bogura jail, died while undergoing treatment at the Shaheed Ziaur Rahman Medical College and Hospital under police custody on Tuesday.
The deceased was identified as Emdadul Haque Bhuttu, 51, vice-organising secretary of Dakkhinpara union unit of Awami League in Gabtoli upazila of the district.
The AL leader was sent to jail in a case filed for vandalism and explosive act on February 26, said jailer Syed Shah Sharif.
Emdadul fell sick after having sehri, the pre-dawn meal for Muslims during Ramadan, early Tuesday and was taken to Shaheed Ziaur Rahman Medical College and Hospital.
Primarily, it is suspected that he died of a cardiac arrest.
So far, four leaders of Awami League have died in Bogura jail since August. They were Bogura district unit AL organising secretary Shahadat Alam Jhunu, Durgahata union unit AL former chairman Abdul Matin Mithu, Shibganj upazila unit AL treasurer Abdul Latif, and general secretary of no 15 ward of Bogura municipality Shahidul Islam Ratan.