Two former heads of an Indonesian airline are being tried for conspiring in the murder of a leading rights activist.

Former Garuda airlines president Indra Setiawan, and a subordinate, Rohainil Aini, were tried in separate court sessions Tuesday, for their alleged involvement in the poisoning death of Munir Thalib, who was killed on a Garuda flight.

Prosecutors say Aini forged a letter that allowed a key suspect in the case, Pollycarpus Priyanto, to board Munir's flight.

At a trial in August, former Garuda chief Setiawan said Indonesia's top spy agency directed the airline to allow Priyanto to work as a security officer on the airline's flights.

Last year, Priyanto was found guilty of murdering Munir, but Indonesia's Supreme Court reversed the decision. Prosecutors are trying to overturn that ruling.

Munir was a vocal critic of Indonesia's military, accusing it of human rights violations, illegal drug smuggling and illegal logging.

Some information for this report was provided by AP and Reuters.