He became prominent in the news just before the 2004 U.S. presidential election for his study estimating that 100,000 Iraqi civilians had been killed in the Iraq war at a time when official U.S. government counts were much lower.
He did post-graduate fellowship work with the Centers for Disease Control in Atlanta and obtained a Ph.D. in environmental engineering from Johns Hopkins University in 1992; he has been a regular lecturer there ever since.
[4] In opposition to the study's claims, an official Ministerial Statement from the United Kingdom Parliament stated that "the Government do not accept its[The Lancet study's] central conclusion", noting that the Iraq Ministry of Health figures, which were collected from daily hospital reports, showed 3,853 civilian deaths and 15,517 injuries between April 5, 2004 and October 5, 2004.
The study was also published in The Lancet, and reported: "We estimate that between March 18, 2003, and June, 2006, an additional 654,965 (392,979–942,636) Iraqis have died above what would have been expected on the basis of the pre-invasion crude mortality rate as a consequence of the coalition invasion.
Roberts campaigned for office in 2006, running in the Democratic primary for the U.S. House of Representatives seat of the 24th Congressional District in Chenango County, New York.