Mexican officials persuaded the U.S. Congress to remove some human rights conditions, but a provision prohibiting Mexico from using testimony derived from tortured witnesses remained in the final bill.

“The only thing that I thought when I saw those videos was ‘Thank God the U.S. Congress attached some human rights conditions,’ ” said José Miguel Vivanco, Americas director for New York-based Human Rights Watch.

The Guanajuato state human rights commission has launched an investigation into the police training methods in Leon, and state prosecutors have also said they will review the videos.

But local officials have defended the training methods.

Leon Mayor Vicente Guerrero told reporters that police need aggressive training methods to confront the threat of drug cartels suspected by law enforcement officials in more than 1,800 killings this year.

“Perhaps it looks inhuman to us,” Guerrero told El Heraldo de León. “But it is part of a preparation method that is used all over the world.”