Dr GM Abdul Kuddus, a livestock officer of Morelganj upazila, carried out the autopsy on the carcass of the big cat.
Three samples were taken from the carcass to find out the reason behind the death. The samples were sent to the Forensic Lab of the Forest Department in Dhaka.
The tiger might have died due to old-age complications 3-4 days before its carcass was recovered, said Dr Abdul Kuddus.
Meanwhile, a three-member probe body, headed by Joynal Abedin, assistant forest conservator of the Bagerhat Sadar Range, was formed to look into the death of the tiger. The committee was asked to submit its report within three working days.
The carcass of the tiger was recovered from near Kabar Ali canal in the Sundarbans under Sharankhola upazila on Monday.
The lower portion of the carcass might have been eaten by crocodiles, said Mohammad Belayet Hossain, divisional forest officer (DFO) of the Sundarbans East zone.
According to the forest official, 22 tigers died in the Sundarbans from 2001 till date.
Of them, 10 were killed by poachers, five in mass beating, six died due to old-age complications and one during cyclonic ‘Sidr’.