Indonesian police are looking into the sudden death of an official who fought against a controversial gold mine, following calls for an investigation.
Helmud Hontong, deputy regent of Indonesia's remote Sangihe islands, died during a flight last Wednesday.
Rights groups say his death falls into a pattern of violence of people threatened for standing up for environmental rights.
The 58-year old politician appeared in good health before his flight on Bali island, but 20 minutes into the flight began feeling dizzy, according to his aide travelling with him.
He then "lost consciousness and blood flowed from his mouth and nose" soon afterwards, Hermen Kontu told Reuters news agency.
He was declared dead on arrival at the Sultan Hasanuddin International Airport in Makassar city.
While authorities have said the suspected cause of death was a chronic illness and heart failure, police are doing additional investigations.
Mr Hontong had been a strong critic of a 42,000 hectare gold mine project on his island.
Mining firm PT Tambang Mas Sangihe had received the concession for the mine in January but the opponents of the project say it threatens the islands forests, birds and the water supply to the islanders.
On 28 April, Mr Hontong wrote to the responsible ministry urging authorities to revoke the permit over environmental concerns.
Indonesia's human rights commission Komnas HAM, said it had asked police to investigate the case after complaints from Sangihe islanders, mostly farmers and fishermen.
Amnesty International said the politician's death fell into a pattern of violence and threats against people fighting for environmental and land rights issues.
But Alfred Pontolondo, coordinator of the Save Sangihe Island environment group, said he didn't want to "speculate on his death".
"Let the police process it legally if there's any suspicion."