MADRID, Spain (AFP) — Spanish police on Monday identified as Brazilian a couple and their two young sons found hacked to pieces in a house near Madrid, in a suspected revenge killing.

Police said there was no evidence of a break-in at the house in the village of Pioz where the bodies were found on Sunday after neighbours reported a strong odour emanating from the building.

“There was no sign that any door, any window was forced open,” a police spokesman said.

“We are still not sure about the motive. It seems like it was carried out by professionals,” he added.

The family were from Brazil and while their ages have yet to be confirmed, the two boys were “very young”, born in 2015 and 2012, he added.

Police suspect the bodies had been inside the house for about a month.

“Everything indicates it could be a settling of scores,” Jose Julian Gregorio, the central government’s representative in the region of Castilla-La Mancha where Pioz is located, told reporters.

Police said they could not give further details while the investigation was under way but Spanish media reported that the bodies were found in plastic bags that had been sealed shut with tape.

“The way the bodies appeared indicates an intention to try not to leave clues and get rid (of the bodies),” Jose Garcia of the Spanish police’s UCO unit which specialises in complex investigations, told radio COPE.

“It gives the impression that they pulled out at a certain moment because it is not logical that the bodies were left there,” he added.

Neighbours interviewed on television said the family were renting the house and were rarely seen in the streets since they moved in at the end of July.

The house, which has a pool, has been cordoned off by police. It is located in a residential development with 24-hour security.

Pioz, with a population of around 4,000, will mark a minute of silence on Tuesday at noon in memory of the victims.

The village was “devastated” by the discovery of the four bodies and has declared two days of mourning, Deputy Mayor Sandra Marin said.

“We are very shocked. It is a quiet village,” she said.