NEW YORK (AP) – The Senate’s top Democrat says the federal government must do more to investigate the deaths of Americans who traveled to the Dominican Republic. Sen. Chuck Schumer says he’s asked the Bureau of Alcohol, Tobacco, Firearms and Explosives to step in to lend investigative support after at least eight Americans died this year on the Dominican Republic. Family members of some of the tourists have raised the possibility the deaths may have been caused by adulterated alcohol or misused pesticides. Schumer said Sunday the ATF is uniquely positioned to provide technical and forensic expertise and has offices in the Caribbean. Tourism Minister Francisco Javier García says autopsies show the tourists died of natural causes, though some were pending further analysis. An ATF spokeswoman didn’t immediately respond to a request for comment.