Juárez police chief Roberto Orduña Cruz resigned Friday after the drug cartel killed six city police officers this week and threatened to kill more unless he left the force.

Juárez Mayor José Reyes Ferriz and Orduña announced the resignation at a news conference.

"I cannot place my sense of duty above the lives of my officers," said Orduña, a former army major who was hired last May to oversee the department of 1,600 officers.

At the conference, Reyes also said organized crime wants to control the city's preventive police force, but "we will not permit any criminal organization to interfere with the work of law enforcement."

Earlier Friday, unknown assailants gunned down police officer César Ivan Portillo and Cereso jail guard Juan Pablo Ruiz.

On Tuesday, an armed commando killed Sacramento Perez Serrano, the police operations director and a former army captain, and three other officers who were with him. Police said 150 rounds were fired at the four men.

After each attack, cartel operatives left signs threatening to kill a police officer every 48 hours unless Orduña quit the force.

Orduña had recruited Perez to help get rid of police suspected of working for the Juárez drug cartel.

Tuesday's events proved a turning point for Orduña's tenure. Four officers were killed, and protesters allegedly paid by the cartel blocked three of the international bridges in Juárez.

Mexican officials alleged drug cartels also orchestrated protests in other parts of Mexico, including in Reynosa, to frustrate the military crackdown against drug traffickers.

Texas on alert

Concerns over the border protests prompted the Texas governor's office on Tuesday to place its operations center for border contingencies on alert, said Katherine Sessinger, a spokes woman for Gov. Rick Perry in Austin.

"This is the initial phase of the contingency plan, called increased coordination, but they stood down once it was determined there was no spillover of the violence," Sessinger said. "We will continue to monitor the situation."

El Paso Mayor John Cook said, "It's very dangerous times in Juárez, especially for somebody in law enforcement. It means we have to be prepared and have a plan, and I think you will see (a plan) next week from the (Texas) governor's office."

James Kuykendall, a retired DEA official and author of "O Plata O Plomo?" (Silver or Lead?), a book about the 1985 murder of DEA agent Enrique "Kiki" Camarena, said he is skeptical about Mexico's progress in its battle against drug cartels.

"Corruption is the main cause for why things aren't getting better," said Kuykendall, who worked with Camarena in Mexico. "They gave the country away 25 to 30 years ago to the drug cartels. For things to really change, the Mexican government has to have the political courage to arrest the real criminals and put them in jail."

In light of the continuing violence, the U.S. State Department on Friday renewed its travel alert for Mexico. According to the alert, "Some recent Mexican army and police confrontations with drug cartels have resembled small-unit combat, with cartels employing automatic weapons and gre nades. Large firefights have taken place in many towns and cities across Mexico, but most recently in northern Mexico, including in Tijuana, Chihuahua City and Ciudad Juárez."

Mexico promotes travel

The Mexican Embassy countered the warning with its own statement.

"Mexico has been in the top 10 list of international travel destinations for some years now, and continues to be the number one international tourism destination for U.S. citizens traveling abroad," said Ricardo Alday, spokesman for the Mexican Embassy in Washington. "In 2008 alone, more than 22 million international tour ists visited Mexico, a 5.9 percent increase from 2007 levels."

Toby Friedl, security analyst for Latin America at iJET Intelligence Risk Systems in Annapolis, Md., said that three days ago, a couple of his company's clients in Mexico had to stay an extra day at a hotel when the border was closed because of shootouts in Reynosa in Tamaulipas state.

Another gunbattle Thursday involving police and suspects in Matamoros led the Cameron County Sheriff's Office to temporarily close the southbound Gateway International Bridge at Brownsville, The Associated Press reported.

"Others, some executives, have restricted their travel to Mexico," Friedl said. "We advise them on safety precautions on a case-by-case basis."

IJet, founded in 1999, says it helps protect international travelers with technology and intelligence, and helps identify and recommends measures to respond to global threats.


Border violence
Sources mentioned in this story:
- The U.S. State Department extended its travel alert to Mexico, and urged U.S. citizens to be careful, avoid unfamiliar streets at night and stay abreast of developments. The U.S. consulate in Juárez is at Avenida Lopez Mateos 924-n, telephone (52)(656) 611-3000. http://ciudadjuarez.usconsulate.gov.
- iJET Intelligent Risk Systems is at www.ijet.com.
- A Web site for James Kuyendall's book "O Plata O Plomo?" (Silver or Lead), which is in English, is at www.silverorlead.com/


Travel alert
- The U.S. State Department renewed a travel advisory Friday warning Americans to stay away from prositution and drug-dealing areas along the U.S.-Mexico border.
- The alert recommends visiting only legitimate business and tourist areas.
- The alert said automatic weapons and grenades have been used in clashes between police and drug traffickers.