D.C. police said late Wednesday that they have identified a suspect in the killings of Savvas Savopoulos, his wife, young son and housekeeper, who authorities believe were held captive in the family’s Northwest Washington home. Police said they had obtained a warrant for the arrest of Daron Dylon Wint, who they said is 34 and is from Maryland. They said they do not know his whereabouts. The stunning break in the case came after police matched Wint to DNA found on the crust of a Domino’s pizza that had been ordered to the house the night of May 13, as...