It was the pilot of an Arizona Department of Public Safety (DPS) helicopter called in by a Cochise County Sheriff’s deputy during the Sept. 4 search for two missing Pennsylvania residents who located a burned-out SUV, a series of tire tracks, and a freshly disturbed mound of dirt near the Sunizona home where the missing persons were heading after last being seen alive.
And it would not be long before the information relayed from the pilot of DPS “Ranger” to deputies on the ground below turned the search mission for Duong Nguyen and Robert Atwell into a criminal investigation that led later that day to the arrest of Nguyen’s ex-husband Gregory Michael Carlson. Carlson lived on the 40-acre property in rural, east-central Cochise County with his parents.
CCSO Det. Mike McGeoghegan initially arrested Carlson, 56, on Sept. 4 on two counts of second degree murder. However, last week a Cochise County grand jury issued an indictment in Carlson’s name for two counts of premeditated first-degree murder and five related felony charges.
Carlson has remained in the Cochise County jail on a no-bail order since his arrest, a decision reaffirmed by Judge Laura Cardinal of the Cochise County Superior Court following a Sept. 10 bail evidentiary hearing. As a result, Carlson must remain in custody until his murder trial in mid-2022.
Several details about the search for Nguyen, 30, and Atwell were revealed during the recent bail hearing, including the fact two cadaver dogs alerted to several areas on the large property. Some of the alerts involved the bucket of a tractor, a dug up dirt area, a large fire pit, and the burned out SUV. In addition, bone fragments were found along a narrow trail leading to and from various locations on the property.
But the search of Carlson’s property would not have been possible without information garnered from the DPS pilot’s observations, which McGeoghegan used as the basis for obtaining a search warrant for a thorough inspection of the property where investigators now believe Nguyen and Atwell arrived as planned around 10 a.m. on Sept. 3 for a long-planned child custody swap involving Nguyen and Carlson’s four-year-old daughter.
Items seized as a result of the search warrant, which Arizona Daily Independent has obtained along with McGeoghegan’s probable cause statement for arrest, included several soil samples, a set of keys, a tractor, and Carlson’s pickup truck.
From inside the residence, deputies seized a Winchester 67 single-shot, bolt-action .22 caliber rimfire rifle, a Ruger AR-15 rifle, a Remington 12 gauge shotgun, and a Rossi 20 gauge shotgun. They also took a box for a Sig Sauer handgun although the firearm itself was not located.
Investigators also believe the bodies of Nguyen and Atwell were burned inside the Kia SUV the pair rented at the Phoenix airport on Sept. 2. The fire, which occurred in a large dirt burn pit on the property, reached such high temperatures it resulted in a cremation effect that left mostly small bone fragments along with only three teeth and one 10-inch bone, according to McGeoghegan.
It may take weeks for the Pima County Office of the Medical Examiner to identify each of fragment and for the DPS crime lab to identify other materials recovered from the SUV. Only then will it be known whether it is possible to determine how Nguyen and Atwell died.
McGeoghegan’s probable cause statement provides further details about the frantic efforts undertaken by Nguyen and Atwell’s families back in Pennsylvania who reported the pair missing the morning of Sept. 4 after learning they and the girl did not board a flight back home the night before.
According to the statement, the last confirmed contact anyone had with the Nguyen and Atwell was Sept. 2 after they flew to Arizona. The pair planned to rent a vehicle in Phoenix and drive to Benson to spend the night before going the next morning to Carlson’s residence where the young girl had been staying for a week.
Court records show Carlson and Nguyen were in the midst of a contentious custody battle; an appeal brief had just been filed by Carlson’s attorney on Sept. 1 in an effort to secure additional parenting time with the girl. At the same time, Nguyen was pursuing a child support order.
McGeoghegan’s statement of probable cause notes Carlson resided with his parents, Gerald and Barbara. His mother was present when CCSO Deputy German Paz arrived around 9 a.m. on Sept. 4 in response to the missing persons’ report.
Paz was told by Carlson that Nguyen never showed up for the Sept. 3 custody swap. Carlson and his mother claimed to know nothing about the missing pair’s whereabouts and did not mention undertaking any efforts to contact the mother of his daughter even though she was overdue for the exchange.
With little information to go on at the time, Paz went back on patrol. A short while later, a CCSO deputy in Benson confirmed that Nguyen and Atwell stayed at a Benson hotel on Sept. 2 and checked out around 9 a.m. the next morning. Surveillance footage showed the vehicle they drove away in – a dark colored Kia SUV. It is a one-hour drive from Benson to the Carlson home.
In addition, deputies were informed a 911 dispatcher learned Atwell’s cellphone last pinged to a cell tower in the Sunizona area. The probable cause statement notes Paz searched a large area of desert for nearly two hours in an attempt to locate the phone, the SUV, or any sign of Nguyen and Atwell.
Meanwhile, a sergeant called out the Sheriff’s Search & Rescue team, which in turn requested a response by DPS Ranger. It would not be long before the pilot spotted a burned-out SUV on its roof on the Carlson property. Paz and CCSO Cpl. Jesus Davidson were called back to the scene but found no one home.
The pilot of DPS Ranger directed deputies to the SUV about 200 yards from the house.
“Ranger then guided us to another location approximately 100 yards north of the burnt SUV, where the dirt was disturbed, and where something was possibly buried,” McGeoghegan noted.
A short time later the DPS pilot saw a white pickup, similar to what Carlson drove, approaching the residence’s driveway. Carlson was removed from the vehicle and handcuffed, after which the little girl was placed in another patrol vehicle before being turned over to Arizona Department of Child Safety.
After receiving the Miranda Warning, Carlson once again denied seeing Nguyen or Atwell. As to the burned out SUV found on the property, he claimed an “ugly” SUV showed up in the driveway the day before. Instead of reporting the apparently abandoned vehicle to CCSO, Carlson said he decided to burn in. It would be the first of two post-Miranda conversations Carlson had with McGeoghegan before asking to speak with an attorney.
“Gregory advised the vehicle was just left in the driveway and he was just dealing with it,” according to McGeoghegan. “Gregory was asked why the vehicle was burned out, Gregory responded with a stutter and shrugged shoulders.”
A VIN comparison later confirmed it was the same 2020 Kia SUV rented by Atwell.
One of McGeoghegan’s conversions with Carlson was about two cadaver dogs brought to the property. The detective asked Carlson about an area where the dirt had recently been disturbed, which Carlson said was simply “a clean up” area.
“I asked Gregory if it was just a clean up area then why would the cadaver dogs alert to human remains in that area. Gregory advised ‘that’s a good question, I don’t know.’” Carlson also said he had “no idea” why the cadaver dogs alerted to the tractor’s bucket, the detective noted.
Carlson’s parents returned to their property later in the afternoon and spoke briefly with McGeoghegan.
“I informed them of the burned out vehicle located on their property and human remains observed throughout,” the detective wrote in the probable cause statement, adding that the parents said they left home the morning of Sept. 3 and had not seen any unknown vehicles in their driveway.
“Both parents appeared to be in a state of shock and disbelief but offered no further useful information regarding the case,” McGeoghegan wrote.
Prosecutor Michael Powell of the Cochise County Attorney’s Office told Arizona Daily Independent that at this time he does not expect to charge anyone else in connection to the murders.
Carlson’s divorce attorney, Paul Nordini, asked the Maricopa County judge handling the custody dispute to dismiss that case “until such time as a person other than a parent files a petition for third-party rights.” Nordini also asked to withdraw as attorney in that matter, explaining that Carlson “failed to substantially fulfill an obligation to counsel regarding counsel’s services.”
Several members of Nguyen’s family arrived last week from Pennsylvania. They have applied for temporary custody of the girl.
