Mexican authorities in March blamed "asphyxia by inhalation of toxic gases" for the deaths of four Iowa family members vacationing in the Caribbean resort town of Tulum.
The state attorney general's office in the state of Quintana Roo said investigators were still trying to determine what kind of gas was involved.
The office said in a statement that members of the Sharp family — identified by authorities in their home state of Iowa as Kevin Sharp, 41, Amy Sharp, 38, and their children, 12-year-old Sterling and 7-year-old Adrianna — appeared to have been dead for 36 to 48 hours when their bodies were found Friday during a welfare check at the resort condominium they rented.
Officials said examinations of the bodies indicated the cause of death was hypoxia, or lack of oxygen, and that investigators thus ruled out suicide or violence.
"The bodies ... showed no evidence or traces of violence, nor evidence of anything being disturbed inside the room, so violence from a possible theft was discarded," according to a statement from the attorney general's office.
Mexican investigators were looking into the condo's gas system to determine how the family was exposed to the toxic gas.
Source: NBC News