The samples were part of a collection of materials that had been handed down from researcher to researcher as scientists retired, said Caree Vander Linden, spokeswoman for the U.S. Army Medical Research Institute of Infectious Diseases.

The second researcher to receive the collection performed a full inventory and couldn't account for three vials of Venezuelan equine encephalitis, she said. The discrepancy was reported to the institute's safety officer, and eventually to the Centers for Disease Control and Prevention, which triggered the investigation by the Army Criminal Investigation Command.

During the investigation, one of the researchers who'd worked with the collection recalled a freezer failure at one point that destroyed a number of samples, Vander Linden said.

"Everything in it was basically lost," she said.

This occurred before USAMRIID began using a computerized database to track its samples, and investigators could not find a paper record of the event, she said.

Chris Grey, spokesman for the U.S. Army Criminal Investigation Command, said its investigation into the potentially missing samples is still open.

The investigation found no evidence of criminal activity in regard to the missing samples, he said.

The command is performing a mandatory final review of the case before closing it, Grey said. He would not speculate on when the case would be closed.

Venezuelan equine encephalitis is a virus carried by mosquitoes that can cause encephalitis in humans and horses, according to the CDC.

Death from the disease is rare in humans. Adults usually develop only flulike symptoms before recovering.

The CDC recommends Venezuelan equine encephalitis be handled in biosecurity level-3 facilities, as opposed to BSL-4 facilities where more dangerous pathogens such as Ebola are handled.

Post your comments » Round 2: Snow expected to fall today, Wednesday Fast on the heels of the largest 24-hour snowfall to hit the Frederick County since 1983, meteorologists are predicting another round of heavy snow and wind to hit today. The National Weather Service issued a winter storm warning Monday afternoon for the area, including Frederick County, and said 10 to 20 inches of snow is possible by Wednesday night. Weather-related closings, delays A list follows of weather-related closings and cancellations for this week. Fire and police blotter Police search for robber School closures cause makeup schedule revision Even though Frederick County Public Schools are closed today -- using the sixth snow day this school year -- the school system will not hold school on the Monday Presidents Day holiday as the first scheduled snow makeup day. Crowds pay respect to fallen marine Even U.S. Marines couldn't hold back tears Monday at the viewing of their colleague, Sgt. David Smith. The procession to the Frederick Christian Fellowship Church was led by Frederick County Sheriff's deputies. Dressed in full military regalia, Marines carried Smith's casket into the church followed by family members as more Marines stood at attention.