The poison killed all the fishes of about 39 species and weighing about 800 kg.

Sources said some unidentified men came to the shrine at around 10:00 that night with a five-litre plastic jar, poured poison onto the 6100-sft pond and left the spot.

Night guard Monzurul Alam found the floating jar at around 10:30pm and informed shrine authorities, who detected pesticide inside the can. As dead fishes and sick turtles began to surface on the water, they immediately informed the matter to district administration and police.

District administration has formed a three-member committee headed by Tapan Kumar Dey, divisional forest officer (DFO) and director of Wildlife Preservation Project, to probe the incident. The committee has been asked to submit its report in 10 days.

"It's an attempt to destroy the rare species of our country," Tapan told this correspondent yesterday afternoon. He said the turtles of the shrine, a rare species that cannot be found anywhere else, are believed to be aged between 400 to 500 years.

Until yesterday evening, 120 sick turtles injected with life-saving medicines have been taken to another pond at Kulgaon, 2 kilometres off the shrine, with help of the fire brigade.

Additional Deputy Commissioner (Revenue) Ahmed Murshed said, "We have collected samples of the poison and water will send those to Mymensingh Fisheries Research Institute for chemical test."