St. Louis ? Eleven years later, the chilling imagery of her sister’s murder still makes Pertie Mitchell shiver.

During a burglary, two teens stretched duct tape across Shirley Crook’s mouth and eyes, then muscled her into her van. An hour later, the hogtied woman was dumped off into the murky Meramec River.

“Bubble, bubble,” witnesses later said they heard Christopher Simmons snicker as the woman’s body sank.

“It makes your hands sweat, your stomach sick,” Mitchell said, hoping for the day that Simmons is put to death. “I will be there. I will watch him die.”

The execution is not certain, though. Using the Simmons case, the U.S. Supreme Court will hear arguments Wednesday on whether it is constitutional to execute killers who were juveniles when the crimes were committed.

The court agreed to hear the case after the Missouri Supreme Court last year struck down executions of juveniles and re-sentenced Simmons, now 28, to life in prison, deciding that such executions violate “evolving standards of decency.”

Nineteen states allow executions of killers who were 16 or 17 at the time of the crime. Since the 1976 reinstatement of the death penalty, 22 people — 13 of them in Texas — have been executed for crimes committed as 16- or 17-year-olds.

The U.S. Supreme Court in 1988 barred the death penalty for those 15 and younger.

Right from wrong

Simmons and his attorneys did not reply to interview requests. His advocates have said that executing people who kill as juveniles would be just as wrong as putting to death the mentally challenged, a practice outlawed by the Supreme Court in 2002.

People less than 18 years old, they argue, don’t have fully developed brains and are incapable of making rational decisions.

Mitchell believes Simmons, who was then 17, was old enough to know right from wrong.

“You know how many people get married or join the service when they’re 17 or 18 years old?” said Mitchell, 66. “This man has nothing to justify what he did.”

Simmons’ advocates argue that he led a tough life, from the time his parents separated. Abuse by a relative, they said, included tying him as a toddler to a tree for hours to keep him from wandering while the man fished — or taking him to a bar and plying him with alcohol for the amusement of patrons.

By 13, Simmons was smoking marijuana and swilling hard liquor. He dabbled with mushrooms, cocaine and LSD, and broke into cars and homes.

The crime

About 2 a.m. on Sept. 9, 1993, Simmons and Charles Benjamin, then 15, found an open window at the home of Crook, a neighbor near St. Louis. Crook was sleeping alone inside; her husband Steven — like her, a trucker — was away on the road.

Simmons bound her and forced her — wearing only underwear and cowboy boots — into her van. They drove 16 miles to Castlewood State Park, led her to the middle of the trestle above the Meramec and tossed her into the water.

Two fishermen found the body 12 hours later.

Authorities said Simmons privately boasted of killing Crook because she had seen his face. He was arrested the next day.

“I have a picture in my mind that she can’t see, she can’t speak, she can’t scream out,” Crook’s daughter, Kimberly Hawkins, said at Simmons’ trial. “I can imagine the terror that she’s thinking.”

Prosecutors called the crimes anything but impulsive. They said Simmons believed he could escape punishment because he was a juvenile.

Simmons later claimed that any scheming was “just stupid talk,” and he denied ever believing he could get away with it because he was a minor. He was ordered condemned in 1994.

Benjamin, tried separately as an adult but not eligible for the death sentence, given his age, was convicted and sentenced to life without parole.

In a recent interview with The Associated Press, Benjamin, now 26, said he hoped Simmons prevailed.

“I believe age should factor in some way — not the death penalty,” Benjamin said from prison. Crook’s death, he said, is “not something that can be easily blocked out.”

These days, Mitchell talks of little successes, like paring to one the number of antidepressants she takes to deal with the crime that “never leaves you.”

According to the Death Penalty Information Center, Kansas is one of 19 states where the minimum age for the death penalty is 18.