By Stephen Gibbs
BBC News, Mexico City
Gen Mauro Enrique Tello was killed together with his driver and bodyguard
Mexican officials say they have arrested a drug cartel leader in Cancun who is believed to be behind the murder of a retired general last February.
Juan Manuel Jurado Zarzoza, known as the Puma, was detained on Friday with three other suspected traffickers.
They were found in possession of drugs and weapons, officials said.
In another operation on Sunday, the army arrested 25 suspected drug traffickers in northern Mexico who were apparently disguised as soldiers.
The arrest of Juan Manuel Jurado is being seen as a blow to the feared Gulf Cartel's operations in Cancun.
The city, known internationally as a tourist resort, is also an important base for cocaine-trafficking from South America to the US via Mexico's Caribbean Coast.
Last February, retired Brig Gen Mauro Enrique Tello Quinones from the Mexican army was sent to the city to clean up the apparently corrupt local police force.
Within days of arriving, he was kidnapped, tortured and murdered.
The Mexican authorities say the Gulf Cartel was behind that killing, as well as other drug-running and extortion operations.
Over the weekend the Mexican army also raided a ranch close to the city of Ciudad Juarez on the border with the US after a tip-off.
According to witnesses, the 25 men who were arrested there were wearing soldiers' uniforms.
They were later paraded in front of the press, in civilian clothes, along with a large weapons haul.
Mexican drug cartels have in the past resorted to the tactic of disguising themselves as policemen, and indeed police officers have often been found to have been working for the cartels.
But criminals disguising themselves as soldiers would appear to be a new strategy - perhaps reflecting the fact that it is the army which is now most visibly on the front line in Mexico's war on drugs.