BOULDER, Colo. -- The family of a college student beaten to death 12 years ago told her killer that his life was spared Monday because his victim would not have wanted anyone, even her murderer, to receive the death penalty.

"Her empathy is her killer's greatest salvation," Stephen Chase, the victim's brother, told Diego Olmos Alcalde during his sentencing on Monday. The 39-year-old Chilean national was convicted Friday in the 1997 rape and slaying of Susannah Chase.

Chase's family said they met with prosecutors before the trial to discuss whether to pursue the death penalty but they decided against it because they believed the 23-year-old University of Colorado student would be against it.

"The ironic thing is that the person whose life you stole from us is the reason you won't be sentenced to death today," said Doug Chase, another one of Chase's older brothers.

Boulder District Attorney Stan Garnett said prosecutors considered the wishes of the Chase family, but he could not comment on whether it was determining factor in their decision.

Boulder County District Judge James C. Klein gave Olmos Alcalde the mandatory sentence for first-degree murder, sentencing him to life in prison without the possibility of parole. Olmos Alcalde also received 48 years in prison for sexual assault and 24 years for kidnapping.

Klein ordered the latter two sentences to be served concurrently after the life sentence.

Chase, of Stamford, Conn., had left a pizzeria after getting into an argument with her boyfriend when she was attacked a block from her home in Boulder on Dec. 21, 1997. She was dumped in an alley.

Chase died in a hospital the day after the attack, on the same day she was supposed to fly home to Connecticut for Christmas.

The case went unsolved for 10 years until a DNA sample related to a separate Wyoming kidnapping case linked Olmos Alcalde to Chase's slaying. His half-sister, Ona Bayers, and his ex-girlfriend, Sonci Francis, testified during the trial that days after Chase's death, Olmos Alcalde told them about a similar attack in which the victim was a man he got into a fight with at a bar.

Chase's brother, Stephen, said he hopes that every time Olmos Alcalde sees a "fleeting glimpse of blue sky, or a butterfly" from his prison cell, he will think of Susannah Chase.

"He shall know that it is she who is free at last," he said.

Attorneys for Olmos Alcalde have said they plan to appeal.