Mexico's own corrupt police officers often hinder the country's fight against drug gangs and organised crime but government officials in the state of Nuevo Leon say they have a plan to get rid of corruption, once and for all.

Along with their physical endurance being put to the test, they are also undergoing a series of lie detector tests and psychological exams ina n effort to become the officers who finally change the state's long history of police corruption.

Al Jazeera's Franc Contreras reports from the northern city of Monterrey.