The Honduran environmental activist’s killing a year ago bears the hallmarks of a ‘well-planned operation designed by military intelligence’ says legal source

Leaked court documents raise concerns that the murder of the Honduran environmentalist Berta Cáceres was an extrajudicial killing planned by military intelligence specialists linked to the country’s US–trained special forces, a Guardian investigation can reveal.

Cáceres was shot dead a year ago while supposedly under state protection after receiving death threats over her opposition to a hydroelectric dam.

The murder of Cáceres, winner of the prestigious Goldman environmental prize in 2015, prompted international outcry and calls for the US to revoke military aid to Honduras, a key ally in its war on drugs.

Eight men have been arrested in connection with the murder, including one serving and two retired military officers.

Officials have denied state involvement in the activist’s murder, and downplayed the arrest of the serving officer Maj Mariano Díaz, who was hurriedly discharged from the army.

But the detainees’ military records and court documents seen by the Guardian reveal that:

• Díaz, a decorated special forces veteran, was appointed chief of army intelligence in 2015, and at the time of the murder was on track for promotion to lieutenant colonel.
• Another suspect, Lt Douglas Giovanny Bustillo joined the military on the same day as Díaz; they served together and prosecutors say they remained in contact after Bustillo retired in 2008.
• Díaz and Bustillo both received military training in the US.
• A third suspect, Sgt Henry Javier Hernández, was a former special forces sniper, who had worked under the direct command of Díaz. Prosecutors believe he may also have worked as an informant for military intelligence after leaving the army in 2013.