Police in the central Mexican state of Zacatecas on Thursday found the bodies of six people, including a 13-year-old boy who had been arrested on Feb. 4 as a presumed murderer but was released a few hours later due to his age, a government official said.

The six bodies showed signs of torture and were found Thursday morning on the outskirts of the towns of Morelos and Vetagrande, the head of the Zacatecas state prosecutor's office, Arturo Nahle, told reporters.

According to witnesses quoted by the Zacatecas daily NTR, shots were heard in the area at about 2 a.m., presumably emanating from a clash between rival criminal bands.

The bodies - four of them women - were found after an anonymous telephone call was received by the local emergency services department, the daily said.

The boy whose lifeless body was found with the others had been arrested on Feb. 4 for allegedly participating in 10 killings. Despite the fact that he admitted being the killer in three of the murders, he was released a few hours later.

The boy's release came as a result of the Zacatecas Justice for Adolescents Law, which allows the prosecution of supposed criminals only if they are 14 years of age or older.

Due to the public indignation sparked by the release of a confessed murderer, Nahle proposed reducing the minimum age set by the law to punish younger killers. He called the boy extremely dangerous.

Although no precise figures exist on the number of children and teenagers who might be involved with criminal groups around the country, the Network for the Rights of Children in Mexico calculates that between 15,000 and 20,000 minors are the victims of various kinds of "narco-exploitation."

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