A full investigation into the killing of Chut Wutty must be launched and the Cambodian government pushed to control illegal deforestation and land-grabbing

Chut Wutty, a dedicated Cambodian activist, was shot dead at a military checkpoint by military police last Thursday. At the time, Wutty was driving with two journalists, who were covering a story on illegal logging. The shocking eyewitness account of his death revealed that he was physical and verbally abused, then shot while trying to drive away, and left to die. His death reveals the brutal and callous greed of logging companies and concessionaires, which are looting the country's natural wealth and destroying local communities' livelihoods.

Wutty was a prominent activist, and director of the Natural Resources Protection Group. He had been working to stop illegal deforestation in Cambodia since the 1990s, particularly active in the Cardamom mountains and in Prey Lang forest. In 2011 he played a major role in supporting the Prey Lang network, a grassroots community movement that spans four provinces.

Local authorities and officials offer no support. As Wutty explained:

"They simply put the blame on the forest protectors, the local community, and try their best to conceal illegal actions by businessmen, turning a blind eye and deaf ear on them. According to the law, those living surrounding the forest have the right to access non-timber forest products. They are entitled to use timber from the forest to build their houses. In contrast, this access is denied."

Wutty was perfectly aware of the risks he was taking but he was determined to speak out. Sitting next to him as the military approached at the Prey Lang protest in November, Wutty was composed. "They are coming to catch me; should I run away? But where to go?" He looked around for a second, then mildly commented: "Well, I'd like to see what they do."

A few minutes later he was grabbed in a stranglehold from behind, and wrestled by a military officer. For about a minute he struggled, amid a circle of military and policemen pointing AK-47s. The protestors then came up behind and rushed to his aid, armed only with sticks. Afterwards, Wutty said he was proud and grateful, and also pleased at the spirit demonstrated by the questions the protestors shouted at the police: "Who pays your salary?" "Why do you bring guns here when we have none?" "We're all Cambodians aren't we?"

Later in the guesthouse at Sandan, Wutty said:

"I understand that if I don't help them no one would … many others in the country only want to be in a senior position and to get rewards: to make more and more money no matter if it is at the expense of others."

Wutty's death revealed just how far those people would go in the face of his courageous and untiring dedication to stop the destruction of Cambodia's forests. It is a triumph that he kept pursuing justice in the face of threats and violence.

The question now is, who sent the soldiers to apprehend Wutty?

Three human rights groups have launched inquiries asking this question. The Cambodian Centre for Human Rights president, Ou Virak, said this week that his organisation had strong leads on which company asked the military police to stop Chut Wutty.

The truth may not come out immediately, but a full investigation should now be launched and the Cambodian government pushed to control the illegal logging and land-grabbing by military and companies in Cambodia.

• Fran Lambrick is making a documentary on deforestation in Cambodia and Chut Wutty