As of Tuesday afternoon, the state lab was still analyzing evidence it has received from Charlottesville police, including nearly two dozen items and eight "known samples that we would use for comparison purposes," said Jeffrey Ban, director of the Department of Forensic Science's Central Laboratory in Richmond.

Ban said that the department has expedited the case and hoped to provide authorities with results in the "very near future." But he noted the lab could spend hours or even a whole day on a single piece of evidence that may have multiple stains or hairs on it. He also said it is standard procedure to test any samples against those in their database, including those from other missing persons cases in the Central Virginia area.

Matthew was spotted by eyewitnesses walking with Graham out of a bar on the Downtown Mall early Sept. 13, police have said.

Longo last week made impassioned pleas for Matthew to talk to police.

On Tuesday, Longo said he could not provide additional details on the case.

“We need to be very sensitive about the information we share,” Longo said.

As the search for Matthew continued, the chief said, the search for Graham would not stop.