Last week, the animal briefly set its feet back on dry land on World Elephant Day, before dying in the early hours of Tuesday.
"The causes of its death were weakness due to its long journey, physical and mental stress and heart failure," Ashit Ranjan Paul, the director of the Wildlife Crime Control Unit from Bangladesh's Forest Department, told CNN.
The elephant was initially separated from its herd in Assam, India. The hardy beast endured a 620-mile journey that included crossing the Brahmaputra River, a major waterway that cuts through four countries.
After spending weeks in flooded areas, the elephant almost died during a rescue attempt on 11 August.
"When we found the elephant in the Sirajganj district, both the Indian and Bangladeshi teams tried to rescue it," said Ranjan Paul.
The rescuers first tranquilized the animal but it became distressed and charged into a pond, where it promptly fell unconscious. Villages saved the animal by using ropes and chains to pull it from the water.
The rescuers also tried using another elephant to help the exhausted beast.
"We got a pet elephant to drag the stray elephant along. But the elephant was weak from being in water, sometimes up to its knees and sometimes to its neck," added Ranjan Paul.
Ranjan Paul told CNN that his team tranquilized and fed the elephant on August 14, but that doctors observed the elephant's body temperature rise the following day.
In a bid to save the exhausted animal, the rescue team gave it water through a pump, intravenous saline solution to minimize dehydration, and antibiotic injections, but it eventually succumbed to exhaustion.
"The preliminary postmortem examination report has revealed heart attack as the cause [of its death]," said Ranjan Paul.
While there are roughly 24,000 wild elephants and 3,500 in captivity in India, the animals are critically endangered in Bangladesh.
According to the charity Eleaid, both habitat loss and food scarcity have shrunk wild elephant populations to as little as 196. The country also only has about 100 in captivity.
Correction: The elephant went from India to Bangladesh. An earlier version of this article incorrectly described the sequence of events.