Last Updated Aug 22, 2017 5:40 PM EDT
JEFFERSON CITY, Mo. -- Missouri Gov. Eric Greitens announced that he is issuing a stay of execution for a convicted man who had been scheduled to be put to death late Tuesday.
Greitens cited DNA testing conducted in 2016 that "was inconclusive." He made the statement in a press release announcing the stay of execution for Marcellus Williams, 48, who was convicted of fatally stabbing former St. Louis Post-Dispatch reporter Lisha Gayle during a 1998 robbery at her home in the suburb of University City.
"A sentence of death is the ultimate, permanent punishment. To carry out the death penalty, the people of Missouri must have confidence in the judgment of guilt. In light of new information, I am appointing a Board of Inquiry in this case," Greitens said in the press release.
The five member Board of Inquiry will include retired Missouri judges, Greitens said, and it will have subpoena power.
The announcement comes as Williams' attorneys scrambled to stop the execution in its final hours, appealing to the U.S. Supreme Court, as well as the governor. The Innocence Project and the Midwest Innocence Project has also asked Greitens to appoint the independent board of inquiry to evaluate the conviction and death sentence.
Attorney Kent Gipson contends the DNA testing, which was conducted in December, proved Williams' innocence. The tests involved techniques that were not available at the time of the killing and showed DNA found on the kitchen knife used to murder Gayle matches an unknown man, not Williams. Williams' attorneys say three experts conducted independent tests of the DNA.
Missourians for Alternatives to the Death Penalty and other groups had organized rallies and vigils throughout the state ahead of the scheduled execution.
Gipson said the stay of execution was "the appropriate thing to do." He believes large-scale opposition to the execution was a factor in the governor's decision.
"The people have spoken," Gipson said. "This online petition had a quarter of a million signatures. The case has generated a lot of outrage all over the country and the world."
St. Louis County prosecutor Bob McCulloch, however, says the DNA tests "were inconclusive" and "can neither include or exclude" Williams as the killer.
McCulloch says there is "zero possibility" that Williams is innocent of the fatal stabbing that put him on death row.
"He is the one who committed this murder," McCulloch said. "He made his decision 20 years ago to stay in that house. He heard Lisha Gayle walk down the stairs, and all he had to do was leave. He didn't. And now he has to live with that decision - die with that decision."
Boise State University DNA expert Greg Hampikian conducted the DNA review along with two other experts and excluded Williams from the DNA profile on the knife's handle, Hampikian said in a statement released to CBS News. He said the victim suffered 27 cut wounds and 16 stab wounds.
"Since a kitchen knife is often washed or cleaned, it is likely that the last one to use it may leave DNA," the statement said. "In this brutal attack …the repeated force and friction likely caused transfer from perpetrator's hand to handle, especially since a struggle was indicated."
Gipson also cited previous DNA testing of hairs found from Gayle's shirt and fingernails that also excluded Williams, and said footprints at the scene did not match Williams.
The Missouri Supreme Court postponed Williams' execution six days before it had been scheduled on January 22, 2015 to allow time for the new DNA tests, the statement said. Gipson told CBS affiliate KMOV the evidence was dismissed by Missouri's Supreme Court last week.
The new evidence "means in our mind the actual killer is not him," Gipson told The Associated Press last week.
"How innocent do you have to be to avoid being executed?" Gipson told KMOV.
Loree Anne Paradise, a spokeswoman for Attorney General Josh Hawley, said before Greitens' announcement that the office remains confident that Williams is guilty based on other evidence in the case.
"It's just remarkable to me that the attorney general and the other people defending this conviction can say with a straight face that DNA does not trump the evidence that they've submitted," Gipson told KMOV.
In a court filing last week, Assistant Attorney General Michael Spillane wrote that Williams took a bus to the St. Louis suburb of University City, Missouri, on Aug. 11, 1998, looking for a house to break into and chose Gayle's.
Spillane said Williams broke out a window pane to get inside, where he heard water running in the shower. Spillane said Williams went downstairs and found a large butcher knife. When Gayle came downstairs, she was stabbed and slashed. Her purse and her husband's laptop were stolen.
Gayle was a reporter at the Post-Dispatch from 1981 to 1992, leaving to do social work.
Spillane said Williams stole a jacket to conceal blood on his shirt. Williams' girlfriend at the time, Laura Asaro, later asked him why he would wear a jacket on such a hot day. According to prosecutors, the girlfriend said she later saw the laptop in the car and that Williams sold it a day or two later.
The state also cites testimony from Henry Cole, who shared a cell with Williams for three months in 1999 while Williams was jailed in St. Louis on unrelated charges. Cole told prosecutors that Williams confessed to the killing and offered details about it.
But Gipson said the girlfriend and Cole were both convicted felons who were out for a $10,000 reward.
In addition to the murder conviction, Williams is also serving consecutive terms of life in prison for robbery, and 30 years each for burglary and weapons crimes.
Outside Greitens' office in Jefferson City, execution protesters broke into a dance to celebrate the stay, and some wrote a thank-you note to the governor.
"We are glad that you had the courage as a leader to exercise your power to promote truth and justice," the note, which they wrote on the spot, read.
After several years of being among the states with the highest number of executions, the pace in Missouri has slowed considerably. The only execution in this state this year was in January, when Mark Christeson was put to death for killing a woman and her two children.