MEXICO'S human rights commission is investigating police training methods after videos showed a cadet being made to roll through vomit and another having his head shoved into a pit of excrement.
The grainy images of a police training course, apparently partly filmed with a mobile phone camera, caused a scandal in the Mexican media after a newspaper in the central state of Guanajuato posted them on its website last week.
The paper said the video showed courses given by a private security firm to officers in the city of Leon, apparently to harden them to torture that might be inflicted by criminal gangs that have killed hundreds of police in the midst of a turf war over drug smuggling and a government crackdown.
The human rights commission said the nationwide probe would examine whether the courses are used across the country or the case was isolated to Leon.
"We opened the investigation to find out where these courses are being given and to which security forces so we can put an end to all kinds of torture," senior rights commission inspector Raul Plascencia told Mexican radio.
"Instead of providing training to public servants that helps them do their jobs better, they are putting them through degrading treatment."
The videos show police being subjected to harsh treatment by superiors and what appears to be a foreign trainer in jeans and T-shirt giving orders in English.
In one image, men in combat gear pour water up the nose of a groaning officer as they hang him upside down and blindfolded in a hole they say is filled with rats and human waste.
In another, a cadet is made to roll back and forth across a pile of vomit and is then dragged through it.
Mexican authorities say the officers were being trained to cope with high-stress situations they could encounter as the federal police and the army wage war on violent drug cartels.
"If these were acts done with the consent of all involved there is no crime there," Guanajuato's state attorney general Daniel Chowell said last week.
But the videos sparked concern that cadets are learning torture techniques in a nation where analysts say up to half of the police could be in the pay of drug gangs and where rights groups say abuse is common in police detention cells.
"This video suggests that public security institutions are continuing to fail to take seriously the responsibility to eradicate torture and other ill-treatment in the performance of their duties," Amnesty International said last week.
This is perfectly legitimate training to prepare them for patrolling the streets of Tijuana.
Similiar training is used on cadets in Houston (the new capital of Mexico) as well.