From WFLS via AP via WTOP (or something): Man Dies in Fredericksburg Police Custody:
Fredericksburg police were awaiting word Monday on the cause of death of a Roanoke man who apparently died just after being arrested. Police have not released the name of the 37-year-old man, but say he stopped breathing Sunday night in the back of a police cruiser.
Fredericksburg police say the man forced his way into a motel officer and attacked the manager with a knife, then was subdued by the manager and family members until officers arrived.
Police report the man was combative and tried to kick out the windows of the cruiser. They say he was put in leg restraints and minutes later an officer discovered that he was not breathing.
Officers began CPR. He was pronounced dead a short time later at Mary Washington Hospital.
And the probable answer to “why?”, directly from WFLS this time: Suspect dies in custody:
A search of the man’s room resulted in the discovery of narcotics and drug paraphernalia.
The Free Lance–Star has a longer write-up: City suspect dies in custody