Mexico: Authorities found five bodies in Mexico’s northern state of Nuevo Leon on Sunday, adding to three days of violence that left 22 people dead in the region.

The half-naked bodies of three people aged 18 to 30 were discovered in various streets of San Pedro, a suburb of the industrial hub of Monterrey, the town government said.

There were no bullet shells near the bodies, suggesting that the victims were killed elsewhere and then dumped on the street.

‘They were executed. It was a reprisal, without a doubt,’ said a state investigator on condition of anonymity, adding that each body had a head wound.

Authorities are investigating whether the killings are linked to the recent firing of 20 municipal officers, as one body was left near the house of a relative of the police chief, the city government said in a statement.

Two other bodies were found elsewhere around Monterrey.

At least 17 other people were killed in Nuevo Leon since Friday.

The bodies of four people, including pregnant woman, were found in a house in Monterrey on Saturday.

On Friday, 10 men were killed when gunmen stormed a beer distribution center in broad daylight in Garcia, another Monterrey suburb.

Seven of the bodies were found naked or half-naked in what investigators believe was related to a dispute between criminal organizations.

Raul Benitez, a security expert at the National Autonomous University of Mexico, told AFP that the violence could mean that the rival Zetas and Gulf cartels ‘are beginning to move their confrontation to Nuevo Leon.’

The two gangs have mostly battled in the neighboring state of Tamaulipas.

Nuevo Leon was the scene of gruesome violence in the past but had been in relative peace in the last two years.

Benitez said the violence could also be linked to power shifts following 7 June midterm elections in a country where politics and crime often intersect.

Jaime ‘El Bronco’ Rodriguez, a former mayor of Garcia who defied the Zetas, made history by winning the Nuevo Leon governor’s race, becoming the first independent to win a state house in Mexico.