(CNN) The investigation began, authorities said, when they found body parts on the patio of an abandoned house.

Now, less than two months later, Andres Ulises Castillo Villarreal is behind bars, facing murder charges in at least three cases.

Prosecutors in Chihuahua, Mexico, said this week they have also found evidence linking the alleged serial killer to 12 other killings there "committed with a high degree of brutality." They did not provide details about those cases.

Authorities say Andres Ulises Castillo Villarreal could be tied to 15 killings.

Castillo beat two of his alleged victims, then dismembered their bodies, prosecutors said. Investigators found the body of a third victim buried inside his home. He's also accused of sexually assaulting two other men. Prosecutors said the crimes were tied to sex and drugs.

It was not immediately clear whether he had obtained legal representation.