Updated

The mayor and mayor-elect of a southern town disappeared after Mexico's army detained members of the municipal police force and other local officials on suspicion they were working for a drug cartel, authorities said Thursday.

Ciro Diaz Sanchez, mayor of Pueblo Nuevo Solistahuacan, and Pedro Bautista, who was slated to succeed him next month, went missing on Wednesday. That was just days after soldiers rounded up nearly half the town's police force and two city hall officials thought to belong to a gang allied with the Zetas, the cartel that controls much of the state of Chiapas, which borders Guatemala.

The "gang of the bald ones" is believed to have collaborated with the Zetas to move cocaine and marijuana through the region, authorities said.

An official for the prosecutor's office in the state capital of San Cristobal de las Casas said Diaz and Bautista may have been kidnapped by the Zetas or perhaps fled to avoid detention by the army. The official spoke on condition of anonymity out of concern for his security.

The two — both members of the leftist Democratic Revolution Party — went missing ahead of searches of their houses Wednesday, which turned up high-caliber weapons and two stolen cars at Bautista's, the official said.

Nineteen members of the town's 40-strong police force plus the two city hall employees were being held in a jail in San Cristobal de las Casas, the official said.

Other police officers and local officials in neighboring towns were also expected to be detained in the coming days.

Corruption is rampant among Mexico's badly paid and notoriously ineffective municipal police forces — so much so that President Felipe Calderon proposal to abolish them. Under the initiative, presented to lawmakers in October, each of Mexico's 31 states would have just one police department under the command of the governor.

Elsewhere Thursday, banners were hung from pedestrian bridges in several cities in western Mexico complaining that the federal government has ignored an offer by the La Familia cartel to disband if authorities improve security in the gang's home state.

The "narco-banners" appeared in at least five towns and cities in the Pacific coast state of Michoacan, including the colonial capital of Morelia, the state attorney general's office said.

The banners carried the same message: "La Familia Michoacana ... is saddened about the lack of interest from government institutions in our proposal."

The banners refer to a letter, dropped on streets of several Michoacan mountain towns and e-mailed to journalists earlier this month, saying La Familia would disband if the government negotiates with the cartel on protecting Michoacan citizens.

The government has said it does not negotiate with criminals and declined to comment further on the letter.

La Familia emerged about four years ago and quickly earned a reputation as one of the most brutal Mexican cartels. It is known for decapitating rivals and staging bold attacks on government security forces, including an ambush that killed 12 federal police officers in June and a spasm of violence last year in which at least 18 police officers were killed.

La Familia, however, has sought to convince the public that it is defending Michoacan against other drug gangs. It has a set of rules for cartel members that proclaim family values and prohibit consuming — but not trafficking — hard drugs.

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Associated Press writer Gustavo Ruiz in Morelia, Mexico, contributed to this report.