When their 14-year-old son was snatched off the street by armed men in early June, the Marti family reportedly did what many wealthy Mexicans do in such a crisis.

The founders of a chain of sporting goods stores hired a private negotiator to deal directly with the kidnappers. They said nothing to police or to the press. They paid millions of dollars in ransom money. Then they waited for a signal that the boy had been released.

It was not to be.

Fernando Marti’s decomposed, bullet-riddled body was found Friday in the trunk of a stolen Chevy that had been abandoned in a working-class Mexico City neighborhood. For many, Monday’s news was equally bad: Authorities said they had arrested at least one city police commander in connection with the crime, and that other cops might be involved.

The possibility of police involvement comes at an awkward time for President Felipe Calderon, who has been waging a high-stakes war against violent drug cartels since taking office in December 2006.

The campaign against drug gangs as well as other violent criminals has been repeatedly compromised by corrupt police officers, pushing Calderon to turn to the army. As of June, 40,000 soldiers and 5,000 federal police were deployed nationwide. The administration last week also launched a shake-up at the federal attorney general’s office in response to the agency’s ineffectiveness. Officials said Monday that a prosecutor who oversaw extradition of drug traffickers had resigned, the second high-ranking official to leave the attorney general’s office in a week.

Although Mexico City police say they don’t think the gang that kidnapped Fernando was involved in the narcotics trade, many other kidnappers may be. Under pressure from the federal crackdown, some gangs appear to be ratcheting up kidnapping and extortion to make up for shrinking drug profits.

“The authorities knew that if they attacked the drug trafficking and took away that cash flow that the delinquents would look for something else,” said Maria Elena Morera, head of a citizens anti-crime organization in Mexico City. “The tragic death of Fernando Marti symbolizes what many Mexicans are living through.”

There is no question that kidnappings in Mexico are soaring, particularly in trafficking hot spots along the U.S. border, where criminals have found easy targets among business owners, doctors and other professionals who have prospered in the region.

Last year, 438 Mexicans were reportedly abducted, according to official government statistics. That’s a 34% increase over 2006. But it’s believed to be just a fraction of the true number. Experts say many Mexicans are reluctant to contact police out of fear that officers are involved in the kidnapping and will harm their loved ones if they don’t cooperate.

Tijuana is believed to suffer more kidnappings than any city in the world outside Baghdad, according to a global security firm that handles ransom negotiations south of the border. Hundreds of residents have been abducted for ransom in recent years, according to victim support groups.

The arrival of thousands of federal troops has helped fracture drug cartels and in some cases sent them in search of new avenues to make money.

Heavily armed gunmen, often posing as police or working in tandem with crooked cops, have snatched people from shopping centers, restaurants and parking lots. They imprison their victims in networks of safe houses, shackling and blindfolding them. Kidnappers sometimes amputate their victims’ fingers or ears and send them to family members to terrify relatives into paying up.

“The crime of kidnapping is one of the most painful because it affects the victim, the families and friends,” said Morera, whose husband was kidnapped. He survived the ordeal, but had several fingers sliced off.

The surge in kidnappings has motivated thousands of well-to-do Mexicans to flee the country or surround themselves with security.

That was apparently the case with the Marti family.

Fernando’s father, Alejandro, is a well-known businessman who founded a popular sporting goods chain and a string of fitness centers. A self-made entrepreneur, he got his start hawking T-shirts during Mexico City’s 1968 Olympics.

Authorities have released almost no information about the Marti case. But according to press reports, Fernando was riding in a car with a driver and a bodyguard on June 4 when the group was pulled over by men who they thought were police. Armed men killed the adults at the scene and abducted the boy.

One press report said the family paid $6 million for the boy’s release and waited in agony after the kidnappers stopped communicating with them.

The news the Martis had dreaded came Friday when residents of a tough Mexico City neighborhood reported a noxious smell coming from a silver subcompact parked on a residential street. Police found Fernando’s body in the trunk. He had been shot several times. Forensic experts said he may have been dead for as long as a month.

More than 800 kidnap victims have been killed in Mexico since 1970, according to Jose Antonio Ortega Sanchez, president of another citizens anti-crime group, who added that the mayhem was shaking the country to its foundations.

“Here’s the problem: the corruption, the collusion and the involvement of the authorities. . . . If Calderon can’t clean up his own security agencies, he’s not going to be able to advance,” he said.

Fernando was buried Sunday. A front-page photo in the national daily Reforma showed a black hearse followed by a procession of luxury cars. There were so many flowers, according to one report, that they had to be transported to the cemetery in a cargo truck.

The pages of the capital’s newspapers overflowed with sympathy announcements from the family’s business associates and friends, as well as angry letters to the editor.

“Mexico is submerged in an abyss of blood and uncertainty, inconceivable and interminable,” read one.

Mexico City police on Monday identified the arrested police commander as Jose Luis Romero Jaimes, but provided no other information about him.

Also taken into custody was Marco Antonio Moreno Jimenez. News reports had originally identified Moreno Jimenez as a member of the federal police, but capital authorities denied that.

marla.dickerson@latimes.com

Times staff writer Reed Johnson contributed to this report.