NEW YORK — 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.

Family members of the tourists who died have called on authorities to investigate any possible connections. Relatives have raised the possibility that the deaths may have been caused by adulterated alcohol or misused pesticides.

ATF spokeswoman April Langwell said the Treasury Department primarily handles investigations involving potentially tainted alcohol. But she said ATF has offered its assistance and would work with other law enforcement agencies to keep Americans safe.

"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 sicknesses and several deaths of Americans in the Dominican Republic, the feds should double their efforts on helping get to the bottom of things," Schumer said in a statement to The Associated Press.

The ATF primarily investigates firearms-related crimes but is also charged with regulating alcohol and tobacco.

"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 sicknesses and several deaths of Americans in the Dominican Republic, the feds should double their efforts on helping get to the bottom of things," Schumer said in a statement.

Francisco Javier García, the tourism minister in the Dominican Republic, said earlier this month that the deaths were not part of any mysterious series of fatalities but a statistically normal phenomenon lumped together by the U.S. media. He said autopsies show the tourists died of natural causes.

Five of the autopsies were complete as of last week, while three were undergoing further toxicological analysis with the help from the FBI because of the circumstances of the deaths.