WASHINGTON - The Supreme Court blocked the execution Wednesday evening of Hank Skinner, a Texas death-row inmate who says he is innocent and for a decade has sought DNA testing of key evidence at the crime scene.

Acting just an hour before Skinner was scheduled to die, the justices issued a stay of execution and said they wanted more time to consider his pending legal appeal. It will likely be several weeks before the high court decides whether to hear Skinner's case.

Skinner had sued the county district attorney seeking DNA testing of semen and skin samples as well as two bloody knives and a man's windbreaker, all taken from the scene of a triple murder in the north Texas town of Pampa.

Last week, a crime lab in Phoenix offered to conduct the testing at no cost.

Skinner was convicted and sentenced to die for murdering Twila Busby, his girlfriend, and her two adult sons in their home on New Year's Eve in 1993. Skinner contended that an uncle was the true killer.

Police and prosecutors said the blood on Skinner's clothes came from the victims and that he had left bloody palm prints in the house. Skinner said he awoke in a stupor and cut his hand on a broken bottle.

His trial lawyer -- a former county prosecutor -- did not seek DNA testing of the crime scene evidence. Since then, state and federal judges have rejected all of Skinner's appeals, ruling that he had no right to test evidence that he could have tested at his trial.

Ten years ago, the Medill Innocence Project at Northwestern University raised doubts about Skinner's guilt. They found a neighbor who said the uncle had cleaned out his van and replaced its carpet the day after the murders.

Also Wednesday, the justices questioned whether an Alabama death row inmate can challenge his second death sentence with an argument state officials said he didn't use when he was first sentenced to die. Lawyers for Billy Joe Magwood want to argue that state law was changed to make Magwood's crime a capital offense after it had already been committed. Magwood, 58, has been on death row since 1981 for the shooting death of Coffee County Sheriff Neil Grantham in 1979. He got that death sentence thrown out, but then was resentenced to death.

The court will make a decision later this year.

The AP contributed to this report.