Late on the night of June 19 2009, a group of armed men went to a home in Nuevo Laredo, Tamaulipas and kidnapped nine men. 

The nine were members of a team from Sinaloa in town to install telephone towers. 

Hours after the armed men took the technicians, the attackers returned and took their equipment.

Nextel officials brought the case to the attention of President Felipe Calderon, but it is still unresolved. The men are gone.

The case is one of several highlighted in a new investigative report by Mexican news site Animal Politico and InSight Crime. The thrust of the report is that over recent years, at least 36 professionals have disappeared in Mexico under circumstances that suggest they may have been forced to work for their captors.

Specifically, the piece argues, engineers, technicians and others may have been put to work building communications networks. It notes that in the last few years, authorities have dismantled more than 400 antennas and repeaters set up by organized-crime groups.

One network, operated by the Zetas in northeastern Mexico, consisted of 167 antennas and 155 repeaters that linked 1,450 radios and 1,300 cell phones and 1,350 Nextel radioes, all controlled by 70 computers. 

Have these kidnapped professionals been put to work building the networks? The report doesn't prove that, but it poses an interesting question: Why so many of the kidnapped professionals have disappeared without a trace. That is, no bodies have been found, and no ransom has been demanded.

The report gives the greatest attention to the case of engineer José Antonio Robledo Fernández, who was kidnapped on Jan. 25, 2009 in Monclava, Coahuila, while speaking to his girlfriend on the phone. Robledo Fernández was working for construction firm ICA Flour Daniel, had experience installing antennas and spoke perfect English.

Three days after he disappeared, his parents were in a hotel in Monclova where they had gone to find their son. A knock came on the door, and it was the company's the security chief, accompanied by two members of the Zetas organized-crime group. 

"They told us not to go to the police, that they were controling the police in Monclova and in Saltillo, that they would help us and our contact would be ICA's security chief," Robledo Fernández's mother, Guadalupe, said.

The parents went to the police anyway. It turned out the firm had been paying protection money to criminals, and the security chief was involved with the Zetas, the report says. Several engineers and other employees had been kidnapped anyway. 

The young man's father, also named José, said: "Sometimes my wife and I have slapped our foreheads thinking it would have been better to negotiate with them, with the criminals, instead of wanting to do things the legal way."

InSight Crime, Animal Político and others are putting out a series of pieces on those "enslaved" by organized crime in Latin America. Here's a piece in English on women enslaved by traffickers, and a piece in Spanish on children.