The prison informant who led police last week to the bodies of two teenage girls buried at a pig farm is now a suspect in their deaths.
Detectives are focusing on the inmate, Roberto Victor Arguelles, because of his knowledge about the cases and his history of violent sexual offenses, according to sources close to the investigation.Arguelles, 33, was convicted of aggravated sexual abuse of a child in May 1992 and is serving an 18-years-to-life sentence at the Point of the Mountain.
Based on information from him, investigators uncovered the skeletal remains last week of Tuesday Roberts, 15, and Lisa Martinez, 16. The bones, including both skulls, were found in the sludge of a canal at the West Salt Lake farm.
Arguelles, who was on parole at the time of the girls' disappearances, began discussing their cases with a prison investigator 18 months ago. Last week, he "confessed" that he had witnessed the burial of the teenagers in 1992 but did not participate in their deaths, the sources said.
However, investigators believe he may be the killer. They point both to his criminal history and his knowledge of the burial site and circumstances surrounding the girls' deaths.
In 1980, Arguelles, then 18 years old, was charged with attempted capital murder, forcible sodomy and two counts of aggravated assault in the abduction of two Granger schoolgirls.
The sexual assaults occurred March 3 and March 6 when the girls accepted rides to school from a man in a rust-colored pickuptruck. They were taken instead to a marshy area near 1300 South and 5650 West, where they were raped.
Prosecutors said Arguelles stabbed his second victim three times in her back and slashed her throat ear-to-ear, leaving for her dead. But the girl dragged herself to a neighbor's door and was rushed to the hospital, according to court records.
He pleaded guilty two months later to one count of forcible sodomy and the attempted capital murder charge. Third District Judge Christine Durham, now a Utah Supreme Court justice, subsequently sentenced him to two consecutive terms of five years to life in prison.
She recommended at the time that the state Board of Pardons keep "the young man in custody for as long as possible for society's protection," according to news accounts of the day.
But he was paroled less than 12 years later. He soon returned to his sexually deviant behaviors, according to court records.
Police arrested him on Aug. 9, 1992, for molesting two children at an elementary school playground a few days earlier.
Investigators say he approached a brother and sister, ages 9 and 10; told them he was a security guard and then "frisked them."
The younger boy testified that Arguelles also showed him a gun before reaching into the boy's pants and fondling his genitals, the records state.
A jury found the man guilty of two counts of aggravated sexual abuse of a child. Third District Judge Kenneth Rigtrup subsequently sentenced him to two consecutive minimum mandatory terms of nine years in prison.
He, like Durham 12 years earlier, sent a recommendation to the Board of Pardons and Parole that Arguelles never be paroled.
Salt Lake County deputy district attorney Charles Behrens said the judge handed Arguelles such a stiff sentence because of the man's history.
"He was on parole. He'd served 11 years for a very violent offense . . . (Rigtrup) had to take that into consideration," Behrens said.
Defense attorneys have since appealed the conviction to the Supreme Court, arguing that the victims were unduly influenced by a botched photo lineup. The high court is still reviewing the case.