SALTILLO — An alleged "illegal singing" case last week this city in northern Mexico might have wound up as a light source of laughter in the pages of a local newspaper. But when police in Saltillo tried to arrest a man for singing as he walked on the street, telling him he had no permit to sing in public and was disturbing the peace, the incident became a public source of outrage for people all over Mexico.

The police decided not to arrest the man, a young physician, when he took out his cellphone and locals gathered to film the incident with their mobile phones, La Jornada reports. The video was viewed more than 100,000 times within the first two days of appearing online.

The incident shows Mexicans' pervasive concerns about corrupt police and the possibility of being "disappeared," as there is no assurance that a person arrested will actually be properly tried in a courtroom — or even make it home. Reports put the number of missing people in Mexico at about 22,000.

César Ruiz Carrillo, a radiologist, stated after the incident that two policemen intercepted him with their patrol car, and without identifying themselves, said "show me your permit" for singing, La Jornada reported. The physician was told to stop filming the incident and one policeman threatened to get the city regulations forbidding his singing from his car, but "came back with nothing."

A discussion took place as Ruiz said he had a right to sing and was no criminal but a "working citizen." He later thanked witnesses for filming the incident and assuring his freedom, but specified he did not "receive at any moment any physical or verbal aggression" from the agents.