It was North Dakota's first death penalty case in more than a century. The state does not have the death penalty but it is allowed in federal cases.
Alfonso Rodriguez Jr., 53, of Crookston, Minn., looked straight ahead and showed no emotion as the sentence was announced.
"We hope the need does not arise for another 100 years," U.S. Attorney Drew Wrigley said. "The defendant's acts of the last three decades have brought us to this place at this time," he said, referring to Rodriguez's earlier convictions for assaults on women going back to 1975.
"I know it wasn't an easy decision for the jurors," Sjodin's mother, Linda Walker, said afterward, her voice shaking. "But Dru's voice was heard today."
The jury reached its decision after more than a day and a half of deliberations. The same federal jury convicted Rodriguez on Aug. 30 on a charge of kidnapping resulting in Sjodin's death.
Rodriguez's mother, Dolores, and sister, Ileanna Noyes, cried as the verdict was announced, as did a number of the jurors.
Sjodin, 22, of Pequot Lakes, Minn., disappeared from a Grand Forks shopping mall parking lot on Nov. 22, 2003, and her body was found the following April in a ravine near Crookston. Authorities said she was beaten, raped and stabbed.
Rodriguez, who got out of prison about six months before the killing, was charged under federal law because Sjodin was taken across state lines.
Sjodin's disappearance brought national attention and months of searches by students, National Guard members from Minnesota and North Dakota and others. It also led to tougher sex offender laws in the two states.
Defense attorney Richard Ney said he will first file a motion for a new trial and if that is denied, he will appeal.
"A life is worth saving, no matter who it is," Ney said.
Earlier, in his statements to jurors, Wrigley said the death penalty would be the "right thing, in the right case." He stood near her portrait and asked for justice.
Ney asked the jury for mercy after calling psychologists and Rodriguez's family to talk about his childhood of poverty, abuse and exposure to farm chemicals. Ney also said Rodriguez had been anxious about being released from prison after serving more than 20 years for assaults on three women in 1975 and 1980.
Walker and Allan Sjodin, Dru's father, said they could have accepted a sentence of life in prison.
"Whatever would have happened, we would have been equally satisfied," Sjodin said. "For Dru's sake, this needed to happen."