Armed men rescued the jailed leader of a kidnapping gang as she was being transported from prison to a hospital in this northern Mexican metropolis.
Four guards were taking Gabriela Elizabeth Muñiz Tamez, known as "La Pelirroja" (The Redhead), from Topo Chico prison to Monterrey's University Hospital when they were intercepted on the road by some of the prisoner's associates, who managed to free her without firing a shot.
Muñiz Tamez, 31, and three accomplices were arrested in July 2009 on charges of kidnapping and extorting shopkeepers in the southern part of Nuevo Leon state, whose capital is Monterrey.
The guards escorting her are being held for questioning about the Monday night escape.
Also in Nuevo Leon, state police discovered the severed head of a federal police officer who had been missing since Monday.
"He is already identified, but the Federal Police will provide the details at the appropriate time," Jorge Domene, spokesman for the Nuevo Leon Security Council, told the media.
The Federal Police and Mexican Attorney General's Office will handle the investigation of the officer's murder, Domene said.
The slain federal cop's patrol car was found abandoned early Monday alongside the highway linking Monterrey with Reynosa, a city just across the border from McAllen, Texas. The vehicle had more than a dozen bullet holes.
In a separate incident, assailants traveling in SUVs gunned down three young men late Tuesday in east Monterrey.
Authorities attribute most of this year's more than 700 homicides in Nuevo Leon to turf battles and score-settling among rival drug cartels.