Washington (CNN) -- The Obama administration appealed Friday to the U.S. Supreme Court to delay next week's scheduled execution in Texas of a Mexican national convicted of kidnapping, raping and murdering a 16-year-old girl. 

The execution of Humberto Leal Garcia, who was sentenced to death for the 1994 crimes, "would place the United States in irreparable breach of its international-law obligation to afford (Leal) review and reconsideration of his claim that his conviction and sentence were prejudiced by Texas authorities' failure to provide consular notification and assistance under the Vienna Convention on Consular Relations," wrote Solicitor General Donald B. Verrilli Jr., in a friend-of-the-court brief. 

In a separate document, a letter to Texas Governor Rick Perry, the U.N. High Commissioner for Human Rights asked that he commute the sentence to life in prison, according to Rupert Colville, a spokesman for Navi Pillay. 

The two requests were based on the failure of Texas authorities to grant the 38-year-old Leal -- who has lived in the United States since he was 2 years old -- access to a Mexican consular official at the time of his arrest. 

"The lack of consular assistance and advice raises concerns about whether or not Mr. Leal Garcia's right to a fair trial was fully upheld," Colville said. 

The case "raises questions" regarding compliance with a 2004 International Court of Justice ruling in what is known as the Avena case that the United States failed to fulfill its obligations to 51 Mexicans on death row in U.S. jails when it did not inform them of their right to contact their consular representatives "without delay" after their arrests, he said. 
for what convict?
Humberto Leal Garcia