Dr. Leslie Mootoo, the chief pathologist and bacteriologist for Guyana, performed complete autopsies on 22 November 1978 on the four people who died in Georgetown and on the five people who died at the Port Kaituma airstrip. His reports appear here. See also the FAQ that addresses his findings here.
Two American medical doctors visited Jonestown in the aftermath of the deaths, according to a cable from the U.S. Embassy in Georgetown dated 22 November 1978. Dr. Bruce J. Poitrast, a psychiatrist, and Dr. Lynn Crook, a pathologist, spent five hours in Jonestown on 21 November 1978. They reported their findings, which Ambassador John Burke forwarded to the State Department in Washington, D.C. Dr. Poitrast and Dr. Crook recommended burying the bodies in Guyana, given the state of decomposition of the bodies, which they said were “impossible to identify by visual recognition.” Their report appears here.
On 15 December 1978 the U.S. Armed Forces Institute of Pathology conducted autopsies on seven bodies that were repatriated to the United States, including that of Jim Jones. Under the direction of Col. William Cowan, it appears that Kenneth H. Mueller and Dr. Robert L. Thompson performed the autopsies on Jim Jones, Maria Katsaris, and Carolyn Layton; while Dr. Joseph M. Ballo and Dr. Douglas S. Dixon, conducted the examinations of Ann Moore, Laurence Schact, Violatt Dillard, and Richard Castillo. Dr. Rudiger Breitenecker, a civilian pathologist, was an observer at these procedures. Their reports appear here.
Although there have been rumors that a number of U.S. doctors were present in Guyana to conduct forensic examinations, there seems to be no credible evidence to support these assertions, based on government documents released under the Freedom of Information Act.