Authorities still don't know what caused 21 law enforcement officers to become ill after participating in a raid on a Niagara Falls apartment in December. However, in a statement Thursday, they said all officers have recovered.
The FBI and Niagara County Sheriff said in a joint statement that tests came back negative on materials collected by hazardous materials teams 12 days after the raid.
"914th Air Force Reserve and Niagara County Hazmat personnel entered 4 Packard Court on Wednesday, December 26, 2018, to collect samples for testing," the statement said. "All collected materials have been tested, both biological and chemical, with negative results."
Thirty-nine members of federal and local law enforcement took part in the police activity on Dec. 14.
"In the days that followed, many of the officers and investigators fell ill with various symptoms to varying degrees," the statement said. "A number of people who became sick never actually entered the house. In all, 21 people reported they fell ill and 18 people reported they did not get sick."
However, the FBI and Sheriff said all personnel who were sick have "fully recovered and no longer exhibit symptoms."
They continue to work with the Niagara County Department of Health on the investigation and say they will release results to the community if "definitive findings" result.