On July 22, four mountain gorillas were shot and killed in the Democratic Republic of the Congo’s Virunga Mountains. The remains of a fifth gorilla, a female who had gone missing after the attack, were discovered August 16. Her infant, who had been with her, is now presumed dead.

These six deaths bring the year’s total count to nine, including two that died during fighting between rebel leader Laurent Nkunda and government forces, and a female that was killed in June “execution style,” similar to the July attack.

Because many of the bodies were left intact-that is, no trophy items such as hands and feet were missing-the killings do not appear to be poaching related. International conservationists and local rangers offer another explanation: charcoal.

The demand for charcoal in eastern DRC has increased dramatically in the past decade with the influx of refugees from Rwanda as well as the burgeoning local population. Suppliers have responded by illegally extracting wood from Virunga’s forests. An estimated 90% of charcoal in the region comes from this plundering.

The gorillas-with their rangers and international protection-pose a threat to this $30-million-a-year industry. One park official told the Times Online that “for the charcoal traders, the quickest and easiest way to get access to that forest is to kill the gorillas. If there are no gorillas, there is no one who is going to protect that forest.”

To date, more than 100 Virunga rangers have been killed in the line of duty, protecting the forest and gorillas.

The mountain gorilla is a critically endangered species, with only 700 individuals left in existence according to the WWF. Approximately 170 gorillas live in the DRC’s Virunga Mountains, while the rest are in Rwanda’s Virunga National Park and Uganda’s Bwindi Impenetrable Forest. Tourism to see these rare creatures in the wild brings in crucial support to these countries’ economies.

The deaths of these nine gorillas in the DRC represent a devastating blow to the future of the species and our ability to protect the gorillas that remain.

“This is the worst single incident in 30 years,” said Conservation International president Russell A. Mittermeier to ABC News after the July slaying. “If we can’t stop these attacks, our closest living relatives will disappear from the planet.”