Authorities have recovered 12 bodies in a western Mexican river near a lake popular among US tourists, as suspicion about the deaths turned toward two drug gangs on Thursday.
Three bodies were found in the Lerma river on Thursday afternoon, after nine others were recovered in the first three days of the week, said Eduardo Almaguer, the top prosecutor in Jalisco state.
"Twelve bodies have been found in the Lerma river and its mouth at Lake Chapala," Almaguer told reporters.
He did not say how the three new victims died.
The nine other bodies showed "show signs of violence," he said. A police official said at least two of those victims had bullet wounds and two others were mutilated.
"If two criminal groups participated in this situation, our obligation is to arrest them," Almaguer said, without naming the gangs.
The bodies were recovered within the municipality of Jamay, a fishing area. The lake is also surrounded by a large expat community, including retirees.
The western state has been hit by violence perpetrated by the Jalisco New Generation drug cartel, one of Mexico's most powerful and violent criminal groups.
Almaguer said some victims may have been killed in Jalisco and others in the neighboring state of Michoacan, another major flashpoint in Mexico's decade-long drug war.
Jamay is near the municipality of La Barca, which lies near the Jalisco-Michoacan border, where 75 bodies were unearthed from 37 clandestine graves between late 2013 and early 2014.
In the river case, Almaguer said his office has asked the authorities in Michoacan and the state of Guanajuato for help in identifying the bodies, in case the victims came from those states.
"We don't have any report of abduction, which is why the process of identification and the prosecution of this crime have been slow," he said.
About an hour's drive from Jamay, federal police killed 42 New Generation cartel suspects on a ranch in the Michoacan municipality of Tanhuato in May 2015.
Only one officer was killed in the clash, a lopsided death toll that raised suspicions that police had either used excessive force.
The National Human Rights Commission issued a scathing report last month alleging that 22 civilians were "arbitrarily executed" during the operation.
The report prompted President Enrique Pena Nieto to fire federal police chief Enrique Galindo.
The New Generation cartel had killed some 30 police officers and soldiers in the weeks prior to the Tanhuato incident. In one clash, the gang downed a military helicopter with a rocket-propelled grenade earlier in May 2015.
But the Jalisco gang has also clashed with rival criminals in neighboring Michoacan state, where the Knights Templar drug cartel once held sway.
Farmers formed vigilante forces to counter the Knights Templar in 2013 and the cartel has been severely weakened, but smaller gangs have since emerged and continue to wreak havoc in the state.