HUNTSVILLE, Texas (AP) — Attorneys for a Mexican national on Texas death row for the slaying of a Houston police officer 20 years ago are hoping a federal civil suit will block the prisoner's execution this week.

Lawyers for 46-year-old Edgar Tamayo are suing Gov. Rick Perry and the Texas Board of Pardons and Paroles, challenging what they argue is an unfair and secretive clemency process in Texas.

They also contend Tamayo should have been told he could seek legal help from the Mexican consulate when he was arrested for the January 1994 shooting death of 24-year-old Houston patrolman Guy Gaddis.

Tamayo is set for lethal injection Wednesday evening in Huntsville. Attorneys say he was in the U.S. without legal permission and prison records show he had a criminal record in California.

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