Houston ? Mexico is seeking clemency for one of its citizens scheduled to be executed Wednesday in Texas, contending the Mexican consulate wasn’t notified before charges were filed.

Similar protests in 1993 and 1997 were filed on behalf of Mexican citizens on Texas’ death row including a convicted police killer but both failed.

Javier Suarez Medina, 33, convicted of the Dec. 13, 1988, shooting death of a Dallas undercover narcotics officer, would be the fifth Mexican citizen executed since Texas reinstated the death penalty in 1982. A total of 276 inmates have been executed.

The Mexican government has written to Gov. Rick Perry and spoken with Secretary of State Colin Powell requesting clemency in Suarez’s case.

The Mexican government only learned about the capital murder charge and death penalty after the 1989 trial. Mexico claims Texas’ failure to inform officials sooner violated the Vienna Convention, which requires letting detained foreign nationals contact their consulates for help.

“Whenever a Mexican citizen is facing the death penalty, prompt and extensive consular support is provided to ensure that the defendant has every means necessary to mount a full and fair defense,” the Mexican Embassy wrote. “In case after case, timely assistance from the Mexican authorities has literally meant the difference between life and death.”