What did this man do to the Yanomami?

Did James Neel, a geneticist working on a grant from the Atomic Energy Commission, commit an act of mass murder? In 1968, did he, in a fiendish experiment that resulted in hundreds of deaths, intentionally unleash a measles epidemic on a population of Yanomami Indians in Venezuela? It seems extremely unlikely. Was he, instead, guilty of some kind of mass manslaughter, by intentionally using an outdated and extremely powerful vaccine on a notoriously vulnerable and immune-deficient population, then skipping off with all the trained medical personnel in the area as the epidemic spread? We'll probably never know for sure.