An American Gulf War veteran and his stepson, being questioned by police in Maryland, are believed to have been behind the series of shootings in and around Washington which has left 10 dead and three seriously wounded.
The two, Mr John Allen Muhammad (41) and his stepson, Mr John Lee Malvo (17), were arrested early yesterday at a lay-by on an interstate highway in Frederick, Maryland, about 50 miles from the US capital.
Although the investigation was still in its early stages, senior law enforcement officials were reported to be confident that the hunt for the sniper could now be called off.
Earlier, the police had announced that they were looking for a Blue 1990 Chevrolet with New Jersey licence plates, and a call was received after about an hour from a motorist who had spotted a vehicle matching the description.
Heavily-armed police surrounded the vehicle. The two men were taken into custody without incident and their car was hauled away in a trailer for inspection. A rifle with a tripod and a telescopic sight was reportedly found in the car. It appears that the pair were asleep in the vehicle at the time of the arrests.
Mr Muhammad is understood to have served in the US army for about 10 years from the mid-1980s and is believed to have changed his surname from Williams last year after he converted to a form of Islam. He served in the Gulf War in 1991 and was described yesterday as "100 per cent soldier". He lived at Tacoma, in Washington State on the US west coast, for most of the 1990s. Police searched a house in Tacoma on Wednesday night and reportedly took away a tree stump used for target practice. It is also believed that hotels in the Washington area were being searched.
The younger man, Mr Malvo, was reported to be a Jamaican citizen. The two were not immediately charged with the sniper shootings, although Mr Muhammad was charged with violating US gun laws. Pending official notification of the all-clear, many schools in the Washington vicinity were still being extra cautious.
A parallel investigation is being carried out in Alabama, where Mr Malvo was linked to a robbery and murder outside a liquor store on September 21st. Police Chief John Wilson of Montgomery, Alabama, said there were "very good similarities" between a police sketch of Mr Malvo and the suspect in the liquor store killing, but that the bullet used was not the same as the .223-calibre ammunition in the Washington attacks.
The sniper struck at random over a period of three weeks against ordinary people going about their business. A three-page letter in broken English apparently demanded a $10 million payment to stop the attacks. The officer in charge of the investigation, Montgomery County Police Chief Charles Moose, used his media appearances to send five messages to the killer in an apparent attempt to lure him into a trap.