Two monkeys that had been part of a decadelong animal-rights battle were put to death Friday hours after medical researchers received U.S. Supreme Court clearance to euthanize and experiment on them.

The macaques Titus and Allen were among 17 monkeys confiscated by authorities from a Silver Spring, Md., lab in 1981 amid charges of cruelty.The National Institutes of Health was given custody of the animals and housed them and two others at Tu-lane University's Delta Regional Primate Center in Covington, 30 miles north of New Orleans.

The pair were killed within hours of the Supreme Court ruling, said Peter Gerone of the center.

"The animals slipped from surgical anesthesia to death with no problems whatsoever," Gerone said.

Brain and euthanasia experiments were performed on Titus after he was put to sleep and before he died, Gerone said.

"I think it's best for the monkeys and I'm glad for them that we can do something to relieve their suffering," he said.

The government said experiments already conducted on the animals could aid the rehabilitation of stroke and accident victims. Gerone said the brain experiments for Titus and Allen could provide valuable information for the treatment of brain injuries.

People for the Ethical Treatment of Animals (PETA) had been trying for years in court to win custody of the animals, saying the NIH did not properly care for them.

Five of the animals were placed in a zoo after being taken from the Maryland lab. Eight had died or been destroyed before this week.

Titus and Allen were left with no feeling in their arms because nerves had been severed during the Maryland experiments. Because of this, they had mutilated their arms by biting and scratching without feeling any pain.

Animal-rights groups tried to stop the euthanasia in federal courts.