A powdery substance found inside a Georgetown University dorm Tuesday morning has tested positive for ricin.
According to a letter from the school's chief of police, the ricin tested negative for any biological threat agents.
Authorities were called to McCarthy Hall in the 3700 block of O Street NW early Tuesday morning for the possibility of ricin in the building.
"There is no immediate threat to members of the Georgetown community," Chief Jay Gruber wrote. "The university consulted with the D.C. Department of Public Health, which informed us that anyone exposed to ricin would have presented with severe symptoms within 24 hours. This window has passed and there are no reports consistent with ricin exposure."
The dorm has since reopened. FBI agents are working with D.C. and campus police to determine who is responsible for leaving the ricin.