The state of Texas executed Mexican citizen Ruben Ramirez Cárdenas, 47, late Wednesday night via lethal injection after a last-minute appeal by his attorneys to the US Supreme Court to halt his scheduled execution was rejected. The execution had been denounced in advance by the Mexican government and by international human rights advocates.

Cárdenas had been convicted and sentenced to death in 1998 for the abduction and murder of his 16-year-old cousin, Mayra Laguna, the previous year. Cárdenas insisted that his confession to police had been coerced and maintained his innocence even as he was ushered into the death chamber in Huntsville, Texas.

“I will not and cannot apologize for someone else’s crime, but, I will be back for justice. You can count on that!” Cárdenas declared in his final written statement.

According to his legal team, the evidence used against Cárdenas was faulty and the confession used in his trial was forced under pressure from the police. His attorneys had also argued that state officials violated his rights by not allowing new-found evidence to undergo DNA testing.

Notably Cárdenas was not given an attorney until 11 days after his arrest, during which time he was interrogated freely by police. Furthermore, Cárdenas was never given the chance to speak to Mexico’s consulate after he was arrested, in violation of international law.

Cárdenas’ attorney, Maurie Levin, argued that evidence used against Cárdenas is now obsolete.