TEGUCIGALPA (Reuters) – Amnesty International and other non-governmental organizations on Tuesday criticized the official investigation into the murder of an environmental rights activist in Honduras, urging foreign experts to intervene.

Five days after Berta Caceres was shot and killed in her home, the police have not presented an official hypothesis and are still considering labeling the murder a common crime, to the consternation of family and friends who believe the death was tied to her fight against large-scale hydroelectric plants and mines.

“Amnesty International demands that this investigation be done with the help of independent forensic experts and with an international commission that will guarantee its impartiality,” Erika Guevara, Amnesty’s Americas director, said at a press conference with other local NGOs.

Caceres, who had received death threats, won the Goldman Environmental Prize last year for her struggle to prevent the construction of a $50 million dam that threatened to displace hundreds of indigenous people.

“We don’t have confidence in the government’s investigations and its security forces,” Olivia Zuniga, Caceres’s daughter, told Reuters. “They were the (same) officials that awarded the concession for the dam that my mother fought against.”

The police have released the only suspect arrested after the murder, Caceres’s former partner and colleague, a police source said, speaking on condition of anonymity.

(Reporting by Gustavo Palencia; Writing by Anna Yukhananov; Editing by Robert Birsel)

Photo: Activists hold photos of slain environmental rights activist Berta Caceres after her body was released from the morgue in Tegucigalpa, Honduras, March 3, 2016. REUTERS/Jorge Cabrera