Five-month-old Ndeze Heidrun Simm. Courtesy Dian Fossey Gorilla Fund International

Authorities still do not know who has been murdering mountain gorillas in Congo’s Virunga National Park, as my colleague Scott Johnson detailed in this week’s cover story. But as word of the seven murders—some call them assassinations, since they may be intended to send a political message to park officials and rangers—spreads through the conservation community, a sense of their enormity is now setting in.

“This is the worst single incident in 30 years, in a region that is normally seen as the only success story for gorillas across the continent,” said Russell A. Mittermeier, president of Conservation International and chairman of the Primate Specialist Group of the IUCN’s Species Survival Commission. “If we can’t stop these attacks, our closest living relatives will disappear from the planet.”

One of the mysteries of the murders is that the killers left valuables behind: two gorilla infants. A baby can bring thousands of dollars on the black market. But 5-month-old Ndeze, as park rangers named him, survived the July 22 attack by unknown assailants on the Rugendo gorilla group that killed Senkwekwe, the dominant silverback, and three adult females (another adult female is missing and presumed dead). Ndeze was carried by his brother from the slaughter; both were later found by members of the Mountain Gorilla Veterinary Program and Institut Congolais pour la Conservation de la Nature (ICCN). They had to tranquilize the brother to rescue the infant, who would have died from lack of care.