Discovery of skull in Casa Grande septic tank leads to breakthrough in cold case

FLORENCE - When workers in the summer of 2014 were sent to check out reports of a clogged septic tank at a home in Pinal County not far from Casa Grande, they discovered a human skull was at the root of the problem.

The skull became a vital piece of evidence in a six-year-old cold case that had befuddled detectives in Pinal County and Phoenix.

Pinal County Sheriff Paul Babeu spoke Monday morning about the painstaking process of connecting the discovery of two dismembered bodies and a burned truck to the unsolved disappearances of Baltazar Lopez and Azaren Cordova from west Phoenix in 2008.

“The process has been long and tedious and is by no means complete, but we are committed to seeing this investigation through to arrest and prosecution of those responsible,” Babeu said.

The tank was drained and set to dry before detectives and workers from the septic-tank-system company went

on to sift methodically through every inch of the human waste, nearly 2 feet deep. They were able to recover a mostly complete human skeleton from inside the underground tank and the septic-system-maintenance truck, along with extra finger and foot bones.

“When these remains were recovered … (the medical examiner) immediately knew,” Babeu said. “He went through his file and he said this case was connected to a case in 2009.”

In January 2009, deputies had been called to a desert wash near Pinal Avenue and Rodeo Road, where hikers had spotted a human skull. In a further search, deputies discovered a shallow grave nearby that had held more human remains, Babeu said. The Pima County Medical Examiner’s Office determined that the body had been dismembered before being buried in the desert but was not able to identify the body or determine how long it had laid there.

The body was known as “John Doe” until the discovery in the septic tank.

Both bodies showed the same sign of sharp-force trauma and other similar dismemberment patterns, leading the examiner to believe an ax or a machete had been used to sever body parts, including decapitation.

“These were vicious, gruesome murders,” Babeu said.

Detectives began to study the two cases and the 2008 discovery of Lopez’s Ford truck, which had been burned to the frame, on a farm in Maricopa five days after his disappearance. They made contact with Phoenix police’s missing persons bureau and investigators who initially had worked the case.

According to Phoenix police, Lopez, a Mexican citizen, had an extensive criminal history and was involved in the drug trade from Mexico to Phoenix. Detectives associated him with members of the Sinaloa drug cartel.

Cordova, who had no known connection to drug trafficking, had been visiting from Mexico for only two weeks when they went missing, Babeu said.

The men, both 34, told friends they were going to look at a truck in Casa Grande before they disappeared, he said. Detectives were able to piece together that Fausto Negrete-Olivas, 43, had lured the men into the desert, Babeu said. Negrete-Olivas was the prime suspect in the case, Babeu said.

“(Lopez) believed he was owed over $10,000. They told him he was going to be paid that money at that time. … Unbeknownst to him and his guest, they both walked into what was planned to be a murder and execution,” Babeu said.

“We do know that his phone was at a certain place at a certain time and usually the person goes with the phone,” he said. “We’ve pieced together so many pieces of evidence in this case … but I can’t share additionally pieces at this time because we do need to prosecute this case. We want to talk to him and find out more information.”

Babeu said Negrete-Olivas was arrested in 2010 on drug-related charges. Known to be high-level drug trafficker, he was linked to Lopez by confidential sources, Babeu said. In an interview with detectives that year, Negrete-Olivas admitted he had met with Lopez and Cordova but said he was not connected to their disappearance. He told detectives he believed that they had been kidnapped.

In 2013, Negrete-Olivas was released and deported to Mexico.

Both sets of human remains were sent to an out-of-state DNA laboratory in late 2014 to see if the victims could be identified. In July 2015, results showed that the body in the desert was Lopez’s and the body in septic tank was Cordova’s.

“Others may have been involved in this,” Babeu said. “Not just to the plan, but also the murder, the dismemberment of the bodies, and then the disposal.”

Babeu also identified Negrete-Olivas’ brother, 48-year-old Dionicio Negrete-Olivas, as a person of interest in the case, saying detectives were hoping to interview him about the murders.

The brothers were believed to be living in Mexico over the past few years, although their current location is unknown, Babeu said. Detectives believe they have been sighted in the U.S. in Nogales, Arizona.

“These drug cartel murders are happening right here, and this is the evidence. This is literally 30 miles from metro Phoenix that we have a cartel hit,” Babeu said. “It’s a concern of ours . ... Our jobs are to be the protectors.”

“This kind of vicious crime cannot go unanswered,” he said.

Detectives were working with the Pinal County Attorney’s Office and the U.S. Marshal’s Office to locate, arrest and prosecute suspects in connection to this case. Anyone with any information is asked to contact the Pinal County Sheriff’s Office at 520-866-5111.