The planned execution Thursday of a Mexican national has prompted a flurry of appeals on his behalf, including a rare plea from the White House, because of what it could mean for other foreigners arrested in the U.S. and for Americans detained in other countries, according to AP. Humberto Leal, 38, is awaiting a ruling by the U.S. Supreme Court on whether to block his lethal injection in Huntsville. He was sentenced to die for the 1994 rape and murder of 16-year-old Adria Sauceda of San Antonio. The appeal contends that authorities never told Leal after his arrest that he could seek legal assistance from the Mexican government under an international treaty, and that such assistance would have aided his defense. Leal moved to the U.S. as a toddler. Leal's attorneys have support from the White House, the Mexican government and other diplomats who believe the execution should be delayed so his case can be thoroughly reviewed. «There can be little doubt that if the government of Mexico had been allowed access to Mr. Leal in a timely manner, he would not now be facing execution for a capital murder he did not commit,» Leal's attorneys told the Texas Board of Pardons and Paroles in a clemency request rejected Tuesday. «Unfortunately, Mexico's assistance came too late to affect the result of Mr. Leal's capital murder prosecution.» President Barack Obama's administration took the unusual step of intervening in a state murder case when it asked the Supreme Court last week to delay Leal's execution for up to six months. The U.S. solicitor general told the court that Congress needed time to consider legislation that would allow federal courts to review cases of condemned foreign nationals to determine if the lack of consular help made a significant difference in the outcome of their cases. The legislation, backed by the U.S. State Department and the United Nations, would bring the U.S. into compliance with the Vienna Convention on Consular Relations provision regarding the arrest of foreign nationals. Lower courts already rejected the pleas, agreeing with the Texas Attorney General's office that since the legislation hasn't been passed and signed into law, it doesn't apply. At least two measures like it failed earlier in Congress. «Leal's argument is nothing but a transparent attempt to evade his impending punishment,» Stephen Hoffman, an assistant attorney general for the state of Texas, told the Supreme Court. Arturo Sarukhan, Mexico's ambassador to the U.S., wrote numerous congressional members and Texas officials calling attention to the legislation and the case and urged Gov. Rick Perry to stop the punishment. Perry had the authority to issue a one-time 30-day reprieve but made no decision while the courts remained involved. Prosecutors said on the night she was killed, Sauceda was drunk and high on cocaine at an outdoor party in an undeveloped neighborhood of San Antonio and was assaulted by several males. At some point, prosecutors said, Leal showed up and said he knew her parents and would take her home and explain the situation to them. Witnesses said Leal drove off with Sauceda around 5 a.m. Some partygoers found her brutalized body later that morning and called police, prosecutors said. When officers arrived, they found Sauceda's head battered by a 30- to 40-pound chunk of asphalt and evidence that she had been bitten, strangled and raped. A large stick that had a screw protruding from it was left in her body. Leal, a mechanic, was identified as the last person seen with her. He was questioned and arrested. A witness testified Leal's brother appeared at the party, agitated that Leal had arrived home bloody and saying he had killed a girl. Testifying during the trial's punishment phase, Leal acknowledged being intoxicated and doing wrong but said he wasn't responsible for what prosecutors alleged. The question of protection for foreign nationals under the international treaty isn't new. President George W. Bush in 2005 agreed with an International Court of Justice ruling that Leal and 50 other Mexican-born inmates nationwide should be entitled to new hearings in U.S. courts to determine if their consular rights were violated at the time of their arrests. The Supreme Court later overruled Bush, negating the decision from the Netherlands-based court. Jose Medellin, condemned for participating in the rape-slayings of two Houston teenage girls, in 2008 raised a Vienna Convention claim similar to the one pending for Leal. It failed and he was executed.