Washington sniper John Allen Muhammad has been given six life sentences without the chance of parole for a series of random killings in 2002.
Muhammad's accomplice (L) testified against him in the trial
A jury in the state of Maryland convicted him on Tuesday after a six-week trial.
Muhammad, 45, already faces the death penalty for a conviction in neighbouring Virginia.
Ten people died and three were wounded in Muhammad's killing spree in the Washington area in October 2002.
Muhammad, who acted as his own lawyer during the latest trial, had argued he was framed.
He showed no emotion and bowed his head as the sentence was read out by Judge James Ryan.
"You, Mr. Muhammad, have no hope. You have no future. You will spend every day for the rest of your life locked in a cage," Judge Ryan said.
The trial's star witness was Muhammad's accomplice Lee Boyd Malvo, 21, who testified against his former mentor for the first time.
Prosecutors introduced DNA and ballistics evidence to link the two to the shootings which took place over three weeks in late 2002, terrifying people in and around the US capital.
The prosecution team say they pursued the second trial in case the Virginia convictions are overturned on appeal.
Muhammad and Malvo's Maryland victims were James Martin, 55 - the first Washington-area victim - James "Sonny" Buchanan, 39; Lori Ann Lewis-Rivera, 25; Premkumar Walekar, 54; Sarah Ramos, 34; and Conrad E Johnson, 35, the last.
Police as far away as Washington state and the Caribbean island of Antigua have said Muhammad may be linked to shootings in their jurisdictions.
He and Malvo could still face prosecution in connection with shootings in Alabama and Louisiana.