Washington sniper John Muhammad will be sentenced in Maryland today, after being convicted of another six killings.

Investigators hunting a sniper responsible for 10 attacks in the Washington area prepared to release their first wanted poster – a drawing of a white box truck – after it was confirmed today that an eighth death had been linked to the killer.

Police in Washington DC are working on a detailed profile of a suspected sniper believed to have gunned down six people in the city suburbs.