Five police officers and five other suspects were arrested Thursday in the investigation into the assassination of an army general who had been appointed police chief of this northern Mexican town over the weekend.

Brig. Gen. Juan Arturo Esparza was the latest military officer killed after taking over a Mexican municipal police force plagued with corruption. President Felipe Calderon has acknowledged that police forces throughout Mexico are rife with officers in the pay of cartels, and he has relied heavily on the military to fight drug trafficking.

The attack Wednesday had its origins in an illegal quarrying company, said Alejandro Garza y Garza, the Nuevo Leon state attorney general.

He said one of the suspects was facing investigation for operating the company and enlisted the help of a local hotel owner with ties to a powerful drug cartel to intimidate officials in Garcia, a town outside the northern city of Monterrey.

A group of gunmen, believed to belong to the Gulf cartel, arrived at the home of Mayor Jaime Rodriguez to give him a "scare" Wednesday, Garza y Garza said at a news conference. As the group was leaving, they crossed paths with Ezparza, who was driving to the mayor's home after hearing about the threat.

The gunmen sprayed Ezparza's car with bullets, killing him along two former soldiers and two municipal police officers escorting the general, Garza y Garza said. The mayor said told reporters Wednesday he heard the gunshots from his home.

The operator of the quarrying company and the hotel owner were both arrested.

Garza y Garza said the investigation also turned up evidence that at least five municipal police officers had been in the pay of organized crime. The officers were arrested, along three suspected gang members they were accused of protecting. It was unclear if the police and civilians were suspected of a role in the attack against the general.

Earlier in the day, officials shuttered the local police station while state investigators questioned the entire Garcia police force about the killing.

State police moved in to temporarily replace the municipal force, and hundreds of soldiers were deployed to Garcia to reinforce security.

At the Garcia police headquarters, a sign on the door said all activity was suspended. Soldiers surrounded the building. Trucks of state police regularly circled the town hall. Two state troopers with machine guns guarded the driveway leading to the mayor's home.

"We're living in an atmosphere of unease and fear," said Jorge Tamayo, who was strolling the town plaza with his wife and 3-year-old daughter. "We feel that anything can happen to anyone." Continued...