Read more about this story from CNN affiliate WLBT.

(CNN) -- Two Mississippi sisters who have spent 16 years in prison over an $11 armed robbery will be released with an unusual stipulation: One must donate a kidney to the other.

Gov. Haley Barbour, who suspended their sentences, said Wednesday that Gladys Scott, 36, must donate a kidney to her sister, Jamie, 38.

Each of the Scott sisters got two life sentences after they were convicted by a jury of robbing two people near the town of Forest.

Although they would be eligible for parole in 2014, the Department of Corrections "believes the sisters no longer pose a threat to society" and their incarceration is no longer necessary for rehabilitation, Barbour said in a statement.

Jamie Scott's kidney dialysis treatment creates a substantial cost to the state, said Barbour.

Mississippi Corrections Commissioner Christopher B. Epps, who agreed with the decision to suspend the sentences, said Jamie Scott's three-times-a-week dialysis costs the state about $190,000 a year.

The Scotts' attorney, Chokwe Lumumba, said Gladys Scott previously offered to make the kidney donation.

The announcement pleased the NAACP and other civil rights advocates, who have pressed for the sisters' release in rallies and at other forums.

"We need more days like this in Mississippi," NAACP President Benjamin Jealous said at a news conference Thursday at the State Capitol building in Jackson. "We need more days like this in our country."

Jealous said he hoped Barbour's decision served notice to governors in other states where incarcerations are being challenged "that they have a big role to play in advancing justice."

Lumumba praised the decision but said he believed it was the medical situation that brought the sisters' story to the media's attention, rather than the injustice of their conviction. He said he hoped this case would bring further attention to "the story of a lot our people who are in jail who ought not be."

"It was bad when they were convicted in the first place," the attorney said of the Scotts. "It was bad when they were sentenced to two life terms (for a crime) for which most people wouldn't serve a day in jail for."

Lumumba said that while he believes Barbour suspended the sentences "for political reasons," he said the act nonetheless "bespoke a sense of humanity" and thanked him for doing it.

Lumumba contends the sisters were not involved in the robbery and that there were discrepancies in testimony. The convictions and sentences were upheld in 1996 by the Mississippi Court of Appeals.

In 1993, Gladys and Jamie Scott were arrested and charged with leading two men into an ambush in Scott County, according to CNN affiliate WLBT. Court records show the men were robbed by three teenagers who hit them with a shotgun and took their wallets.

According to The Clarion-Ledger, in Jackson, Mississippi, the sisters had pleaded not guilty as accessories but were convicted of armed robbery, while the three accomplices received lesser sentences and since have been released.

"Regardless of what you think of the convictions, they have served more time than they should have served," Lumumba said.

Both of the sisters say they would like to go to Florida to be with their mother and their children, but details must be worked out by corrections officials, Lumumba said. They are housed in different parts of a prison in Pearl, just outside Jackson.

Their mother, Evelyn Rasco, said Thursday she was driving when she got the news.

"I just went hysterical. I had to stop the car," she said. "I got so emotional, thanking God that finally this has come to an end."

It was not clear when the release may occur. Lumumba told CNN it may take about seven days, but Epps said it will be closer to 45 days.

Mississippi officials will work with counterparts in Florida to ensure certain conditions are met, said Epps, adding the women would then have to report to a Florida probation and parole officer.

Barbour said the state Parole Board reviewed the sisters' request for a pardon and "recommended that I neither pardon them, nor commute their sentence.

"At my request, the Parole Board subsequently reviewed whether the sisters should be granted an indefinite suspension of sentence, which is tantamount to parole, and have concurred with my decision to suspend their sentences indefinitely."

The kidney donation "should be scheduled with urgency," Barbour said.

Lumumba, who called the situation a human rights case, said the dialysis equipment at the prison was sometimes faulty and infections were an issue.

But Epps said "we have provided quality care" and complications in dialysis sometimes occur. The state spent about $50 million in inmate medical care in 2010, he said.

Neither of the Scott sisters had a previous record, Lumumba said.

Epps said each have some rules violations reports while serving in prison, but not for anything serious.

Two Democratic Mississippi lawmakers who were involved in the case -- state Sen. John Horhn and state Rep. George Flaggs -- told CNN affiliate WLBT that Barbour deserves credit for suspending the sentences. The governor "brought closure to this issue," Flaggs said.

Lumumba, who said he will press later for pardons, communicated Wednesday evening with Gladys Scott.

"She was just thrilled, and also happy for her sister."

CNN's Martin Savidge contributed to this report.