The 10-year-old male's rotting corpse was found in Blang Awe village in Aceh province earlier this week.
"His tusks were missing and there were traces of blood in the location where he was found," Aceh conservation centre head Sapto Aji Prabowo told AFP.
Officials estimated the animal had been dead for at least a week when the carcass was discovered.
The cause of death was not immediately clear because the body was badly decomposed, Prabowo said.
Tissue samples will be analysed for signs of poisoning.
Rampant deforestation has reduced the species' natural habitat and brought them into conflict with humans, while their tusks are prized in the illegal wildlife trade.
At least 11 wild elephants died in Aceh last year, most of them killed by humans.
In July, a Sumatran elephant was found dead from apparent poisoning in a palm oil plantation.
The environment ministry estimates only around 500 Sumatran elephants remain in Aceh.
Published : November 17, 2018
By : Agence France-Presse Banda Aceh, Indonesia