On a hotel roofgarden overlooking the wealthy Polanco district in Mexico City Carlos Gomez smiles warily as he zips up his jacket to conceal the handgun tucked under his belt. “Things are very dangerous right now,” he says. “There's a lot of violence — too much violence.”

Mr Gomez — handsome, unmarried and in his early forties — is a member of one of the most feared and powerful organisations in Mexico, a group whose members are so far beyond the law that they allegedly kidnapped the 14-year-old son of one of the country's wealthiest businessmen, collected a ransom, then tortured and killed the boy anyway, leaving his decomposing body in the boot of a stolen car.

As any Mexican will tell you, this gang of outlaws is not a drug cartel or a mafia outfit. It is the police.

Mr Gomez — not his real name — is part of it. He earns a meagre $700 (£400) a month as a plainclothes detective with the Procuraduría General de la República (Office of the Attorney General), and is responsible for investigating and prosecuting federal crimes — in theory, at least.

The reality is less comforting: in almost a decade on the force Mr Gomez said that he has solved precisely zero cases. Nada. Not a single one.

“We work with limitations,” he said. “You don't do your job, you just chill out, you take your salary, and you avoid trouble as best you can. Sometimes I get depressed when I think about the situation in Mexico.”

Trouble often comes in the form of officers from rival police departments — there are said to be at least 1,600 of them in Mexico — many of which provide protection to drug cartels or run their own criminal operations. If Mr Gomez raided a “narco store” in the wrong part of town, he would risk being shot or thrown in jail by one of his fellow detectives. Jail can be worse than death so instead Mr Gomez does nothing.

Public distrust of the police has reached such a level that The Times translator made it a condition of the interview with Mr Gomez that it was conducted in a public space, with plenty of witnesses and a CCTV system. Mr Gomez, for his part, said that he was putting his life at risk by talking to the press.

The upshot of police corruption in Mexico has been in an almost total collapse of law and order in recent months, a terrifying state of affairs that seems to have gone largely unnoticed north of the border in the US, even though many Mexicans blame Americans for the troubles. Americans bought the drugs that funded the drugs cartels, which paid off the police, they said. Americans also supplied the weapons.

Now Americans have exported the credit crunch, resulting in a 6.9 per cent slump in the money sent home by Mexican workers in the US, forcing the poor to find other sources of income. “They start out robbing cars,” Mr Gomez said, “then they graduate to kidnapping when they realise that nothing is going to happen to them.”

Much of the evidence is anecdotal, but it is said that 99 per cent of crimes in Mexico go unpunished. That is why a recent study declared that the country now has a worse kidnapping rate than Iraq, with three or four hostages taken each day. The average ransom demand is estimated at $1.4million (£800,000), although the kidnappers will often settle for a few thousand. It is a lucrative trade, with scouts looking for new wealthy victims by attending high society events or joining social networking websites.

Mexicans have had to get used to kidnappings for many years, but the sheer number of them in recent months, combined with the allegation that police officers were involved in the capture and murder of Fernando Marti, the 14-year-old boy, has shocked the country. Several officers were arrested in connection with the Marti case, and the Government yesterday named an elite federal agent, Lorena Gonzalez, as one of the accused. It is thought that Fernando was captured when his driver was pulled over at a police checkpoint.

Mexico City is an apocalyptically dysfunctional place at the best of times, what with the pollution, the flooding, the teetering concrete slums, and the city sinking into the lake bed upon which it was built. Now the fear is turning into anger. At the football match between Mexico and Jamaica last weekend about 75,000 fans dressed in white as a plea to end police corruption — as did the national football team, whose usual uniform is green. A week before, about 150,000 people held a peace march.

Amid the political chaos, however, it is not clear where change will come from. The Mayor of Mexico City, Marcelo Ebrard, does not even recognise the authority of President Calderón after a disputed election two years ago. And Mr Calderón's use of the military against the drug cartels has worsened the situation, causing extreme poverty and more crime in rural areas dependent on drug-trafficking for income.

Some believe that this could be a turning point for the country. “The Mexican people are being very demanding,” Ricardo Escotto, director-general of Grupo Corporativo de Protección Patrimonial, a security companies union, said. “After what happened to Marti, they're saying to the police, if you don't do your job, then quit. And if you don't quit and you continue to not do your job, then you're corrupt. It is a very strong message.”

Mr Gomez said that he knew one of the officers accused of taking part in the Marti kidnapping, and he is, in this case, the wrong man. “He's a badass, he's corrupt, he's a thief, and he has probably kidnapped before, but my guess is that he's not guilty of killing this kid. The real perpetrators are being protected from upon high. The police here have had a lot of power of the past 20 or so years. They're arrogant, they never follow the rules, they torture people, they act with impunity. The corruption is huge. We have to change everything, from the highest level down. It's going to be difficult.”

Crime wave

— A record 2,500 drug-related murders were committed in Mexico last year

— In the first six months of this year there were 323 reported kidnappings in Mexico City

August 1

— The decomposed body of the son of a businessman is found in a car

August 16-17

— Nine people were killed in Cuidad Juárez, and 21 people died in Creel

August 23

— A state police chief was kidnapped and killed, a police officer was killed in Tabasco and nine people were murdered in Chihuahua state

August 28

— Eleven decapitated men were found in Mérida, capital of Yucatán

August 31

— Anti-crime march of more than 100,000 people in Mexico City

September 1-5

— Eighteen decapitated bodies discovered across the country

Source: Agencies

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