PARCHMAN, Miss. (AP) -- The Mississippi Supreme Court has indefinitely delayed Tuesday evening's planned execution of Willie Jerome Manning, who was scheduled to die for the 1992 slayings of two college students.

Manning was originally scheduled to receive a lethal injection at 6 p.m. CDT at the state prison in Parchman. But as the execution time loomed, the high court said the execution should be delayed until it rules further on the case.

The bodies of Mississippi State University students Jon Steckler and Tiffany Miller were found in rural Oktibbeha County in December 1992. They had been shot to death. Manning was convicted in 1994. Prosecutors said Manning was arrested after he tried to sell some items belonging to the victims.

The FBI has said in recent days that there were errors in agents' testimony about ballistics tests and hair analysis in the case.

Manning's lawyers said in filings with the Mississippi Supreme Court that the execution should be blocked based on the Justice Department's disclosures about testimony that it says exceeded the limits of science.

The court ruled 8-1 on Tuesday. The court had previously split 5-4 in decisions in the case.

An FBI letter, sent late Monday, said there was incorrect testimony related to tests on bullets found in a tree by Manning's house that were compared to bullets found in the victims.

That kind of examination "is not based on absolute certainty but rather a reasonable degree of scientific certainty," the letter said.

Manning's girlfriend testified that days before the slayings, Manning had been firing a handgun at a tree behind their house, according to court records. An FBI expert had testified that bullets from the tree matched those recovered from the scene of the crime.

Last week, the FBI said its microscopic analysis of evidence, particularly of hair samples found in a car belonging to one of the victims, contained erroneous statements.

Manning's lawyers had asked the court to stop the execution for additional testing.

In dueling court filings Monday and Tuesday, Manning's attorneys say new DNA testing could exonerate the inmate, but the Mississippi attorney general's office argues that there's overwhelming evidence of Manning's guilt.

Attorney General Jim Hood said in court filings that his office disputes claims by Manning's supporters that DNA testing has never been done in the case. Hood says it was performed in 1993.

Manning's attorneys say that only a blood stain on a shirt from an earlier suspect had been submitted for DNA testing and that the rape kit, hair and other evidence was not tested for DNA. But a filing from Hood on Tuesday said the rape kit and fingernail scrapings produced no evidence to test.

The FBI offered last week to conduct DNA testing after saying its microscopic analysis of evidence, particularly of hair samples found in Miller's car, contained erroneous statements. Manning's lawyers seized on that statement as key to seeking a stay of execution.

In its 5-4 ruling April 25, the state Supreme Court said there was "conclusive, overwhelming evidence of guilt" presented to an Oktibbeha County jury.

The Supreme Court said the jury heard from Manning's cousin and a prison cellmate that Manning has confessed to the slayings. The court said other witnesses testified that Manning tried to sell them items that were later shown to have belonged to Steckler and Miller.

Corrections Commissioner Christopher Epps said Manning will be taken back to Building 29 where death row is located.

On Tuesday, Epps said Manning had expressed optimism to him and the guards outside his holding cell that the execution would be stopped.

"He said he had faith in God and all was in His hands. He said he had faith," Epps said.

Epps said the prison would be taken off lockdown -- a usual procedure on days when there is an execution. He also said officials had contacted members of Tiffany Miller's family about the stay. They had planned to witness Tuesday's scheduled execution and were en route.