Bagus BT Saragih, Jakarta – Activists have expressed concern over the sudden death of Raymond "Ongen" J Latuihamallo, a key witness in the case of slain human rights activist Munir Said Thalib.

Usman Hamid of the Solidarity Action Committee for Munir (Kasum) urged the authorities to be transparent regarding Ongen's health before his death.

"Ongen's family has the right to be informed about the cause of death. It must be medically proven that he really suffered from a heart attack," Usman said.

Another activist Haris Azhar emphasized that the efforts to solve Munir's murder depended on the government's political will.

"This matter is now a political case. The President, the Attorney General's Office and the police are those who hold the most responsibility for the stagnancy of the investigation into Munir's death," Haris said.

"We actually have enough evidence to reveal the truth. So this is pretty much no longer about Ongen," he added.

Ongen died at 56 on Wednesday. As a witness, Ongen once controversially withdrew his testimony on Munir's death. Munir was poisoned on Sept. 7, 2004, while en route to Amsterdam from Jakarta.