Police officers in a small Arizona border city are on heightened alert following a tip that a Mexican drug cartel will put them in its crosshairs if they conduct off-duty busts.
The threat stems from a marijuana seizure made this month by two off-duty police officers riding on horseback in an unincorporated area east of Nogales, a city of roughly 20,000, Police Chief Jeffrey Kirkham told FoxNews.com.
"The word was that these particular officers would be targeted if they were ever in that area again and were not on duty and intercepted any drug trafficking," Kirkham said. "It said they should look the other way."
The unidentified officers were able to confiscate roughly 400 pounds of marijuana during the seizure in early June at a known smuggling corridor along the U.S.-Mexican border where there is "relatively no fencing," Kirkham said. No arrests were made, and the smugglers were able to retreat into Mexico.
Kirkham said his department, which employs 62 officers, learned about the threat through informants and has been unable to determine which Mexican drug cartel is behind it. Kirkham noted that two drug trafficking organizations -- the Los Zetas and the Sinaloa Cartel -- are currently trying to gain a foothold in the Nogales area.
"Which one, we can't establish," he said. "They're not ones to advertise who's behind this. It's difficult to establish."
In response to the threat, Kirkham said everyone in the department was advised to be armed while off-duty. Officials at the Drug Enforcement Agency and U.S. Immigration and Customs Enforcement also were notified, he said.
"We let them know that if they are to go out there, they are to be armed," Kirkham said.
George Grayson, a professor at The College of William & Mary who specializes in Mexican politics and international affairs, said the threat likely came from the Sinaloa Cartel, which is headed by Joaquin "El Chapo" Guzman-Loera, who is being sought by American and Mexican authorities. The U.S. State Department is offering a reward of up to $5 million for information leading to his arrest.
"This is quite credible that the cartels would threaten police officers, on-duty or off-duty," Grayson told FoxNews.com. "They, in fact, are more likely to threaten local police than to go after the [Drug Enforcement Agency] or FBI, which really raises hackles in Washington when you have your federal law enforcement agents threatened."
The Los Zetas criminal organization -- a rival of the Sinaloa Cartel -- had previously operated in the Nogales area, Grayson said, but the area is now probably controlled by "El Chapo," which is Spanish for "shorty." Grayson said Sinaloa is believed to be one of the biggest suppliers of cocaine to the United States, and its members are known to be well-trained and well-armed.
"These officers should get medals for bravery, either on- or off-duty, because I doubt they have the firepower these cartels have," he said. "It's logical that as there are episodes involving U.S. law enforcement [with Mexican cartels], that the threats against American police officers at various levels will also increase."