Four Indonesian men have been arrested over the killing of an orangutan shot some 130 times with an air rifle, police said on Monday, in the latest fatal attack on a critically endangered species. The suspects, farmers from the island of Borneo, admitted killing the animal, saying it ruined their crops at a pineapple and palm oil plantation, according to authorities. “They meant to shoo [it] away but their actions instead killed the orangutan,” said Teddy Ristiawan, district police chief in East Kutai, Kalimantan. New species of orangutan found in Indonesia’s Sumatra island The suspects, who were arrested last week, will be charged with killing a protected animal and face five years’ jail and a maximum fine of about US$7,400. Ristiawan said a fifth suspect, a 13-year-old boy, was arrested but released because he was a minor. Villagers in Borneo’s East Kutai district discovered the male orangutan’s corpse riddled with pellets two weeks ago. Its mutilated body also appeared to have machete wounds. The gruesome killing came about a week after police arrested two rubber plantation workers and accused them of shooting an orangutan several times then decapitating it . The orangutan’s headless body was found floating in a river on the island. Bornean and Sumatran orangutans are listed as critically endangered by the International Union for Conservation of Nature (IUCN). The Sumatran orangutan population is estimated to be just under 15,000, while about 54,000 orangutans are thought to live in Malaysian and Indonesian Borneo, according to the IUCN. The population of orangutans in Borneo has fallen by nearly 100,000 since 1999 , largely due to chopping down forests for logging, paper, palm oil and mining, according to a study published last week in the journal Current Biology . Plantation workers and villagers are sometimes known to attack an animal that they see as a pest, while poachers also capture them to sell as pets.