The announcement was made after three days of deliberations.
The same jury found Cooper guilty of the killings earlier this month. Prosecutors say he shot Osama "Samuel" Haj-Hussein, LeRoy Jernigan, Timothy David Barnwell, Ricky High and Tariq Hussain to cover up a series of robberies throughout the Triangle in 2006 and 2007.
It wasn't until Cooper was arrested in November 2007 for a bank robbery in Garner that police found a 9mm pistol that linked the killings to Cooper.
On Tuesday, tears flowed from the jury box and from loved ones who were disappointed Cooper's life was spared.
"Five and a half hours they come back with a guilty first degree and now two and a half days later they struggle on death penalty," victim's brother John Jernigan said.
Jernigan says the sentence let him and his brother LeRoy Jernigan down.
"Nobody's safe you let this murder go, everybody that kills now they're all free, they have nothing to worry about," he said.
Cooper didn't get the death penalty because some jurors were not convinced he deserved it for each case.
"That's why you saw the jurors cry because they had to realize that we weren't going to convince everybody to go for death and we didn't want them to make a decision that was against probably what they felt deep in their heart," juror William Evaul said.
Cooper's lawyers didn't dispute that he was behind the murders, but they argued that years of physical and emotional abuse by Cooper's father left him with diminished mental capacity and unable to plan the killings.
Prosecutors described Cooper as a cold-blooded serial robber who killed people to prevent them from identifying him.