HUNTSVILLE, Texas (AP) -

Attorneys for a convicted killer of three members of a Corpus Christi family say they'll ask the U.S. Supreme Court to delay his scheduled execution in Huntsville.

Jose Villegas is set for lethal injection Wednesday evening, but his attorneys contend new evidence shows he's mentally impaired and ineligible to be put to death. Their request for more time to investigate the claim already has been rejected by the Texas Court of Criminal Appeals.

The 38-year-old Villegas faces execution for the January 2001 slayings of ex-girlfriend Erida Salazar, her 3-year-old son Jacob and her 51-year-old mother Alma Perez. All were stabbed repeatedly.

When arrested, he was driving Salazar's stolen car and had pawned a television stolen from the Perez home for $75. He had used the money to buy cocaine.