Sao Paulo, Brazil ? An American anthropology professor on a research trip to Brazil was killed Saturday while he was being robbed in a small rain forest town near the Amazon River, an U.S. Embassy spokesman said Sunday.

James Petersen, 51, a professor at the University of Vermont, was robbed at a restaurant in the town of Iranduba, said the spokesman, John Wilcock. Iranduba is about 1,650 miles northwest of Sao Paulo.

Three suspects were taken into custody, according to CBN radio. Wilcock said he could not confirm that information, and federal police in the area were not immediately available for comment.

John Bramley, provost of the university, said Petersen was with colleagues at the time of the robbery and was shot to death.

Petersen, of Salisbury, Vt., chaired the university’s anthropology department, according to the university Web site.