NEW YORK (AP) — The Senate's top Democrat said Sunday that the U.S. government should step up efforts to investigate the deaths of at least eight Americans in the Dominican Republic this year.

The Bureau of Alcohol, Tobacco, Firearms and Explosives should lend support to the FBI and local law enforcement, said Sen. Chuck Schumer, D-N.Y., noting the agency has offices in the Caribbean and the technical and forensic expertise that could aid the investigation.

"Given that we still have a whole lot of questions and very few answers into just what, if anything, is cause for the recent spate of sick...