Khmer Rouge cadres defeated in factional struggles were also liquidated in purges. Man-made famine and slave labor resulted in many hundreds of thousands of deaths.[551] Craig Etcheson suggested that the death toll was between 2 and 2.5 million, with a "most likely" figure of 2.2 million. After 5 years of researching 20,000 grave sites, he concluded that "these mass graves contain the remains of 1,386,734 victims of execution."[552] However, some scholars argued that the Khmer Rouge were not racist and had no intention of exterminating ethnic minorities or the Cambodian people; in this view, their brutality was the product of an extreme version of communist ideology.[553]