The severed heads of two Mexican policemen have been found in the resort city of Acapulco at the site of a recent shootout with drug-traffickers.
The dead men's bodies were found in another area
Both were members of a rapid response unit of the federal Preventative Police which took part in the January shooting in which four traffickers died.
Their heads were dumped outside the city's finance department, 2km (1.2 miles) from the main tourist zone.
The bodies were later found wrapped in a sheet and rug elsewhere in Acapulco.
A sign left with the heads read: "So that you learn to respect."
Gun and grenade attacks in the city this year have claimed at least 12 victims.
Just hours before the heads were found, the governor of Guerrero State, where Acapulco is located, had announced he was investing $12m to acquire heavy-duty weapons, new bullet-proof vests and modernised radios for the police.
"The criminals should watch out because the good weapons are on their way," Zeferino Torreblanca told reporters.