Adam S. Aviles Jr. is technically heading to federal prison because he illegally possessed ammunition. But in handing down the seven-plus-year sentence on Friday, the presiding judge said the ammo appeared to be tied to a more serious crime — the killing of Aviles’ girlfriend, 34-year-old Katheryn “Katie” Ferguson of Cody.

Ferguson went missing last October, and although no body has been found, authorities presume she is dead and suspect Aviles killed her.

Aviles, 26, has not been directly charged in connection with Ferguson’s disappearance, but at Friday’s sentencing in Cheyenne, the prosecution alleged that Aviles committed second-degree murder and killed Ferguson. Assistant U.S. Attorney Paige Hammer presented extensive testimony from the lead FBI agent on the case in arguing for an eight-year prison term.

At the end of the roughly three-hour hearing, U.S. District Court Judge Alan Johnson said he didn’t believe prosecutors had presented enough evidence to support a finding that the ammo was tied to murder. However, Johnson did find that Aviles “unlawfully possessed the ammunition in connection with the voluntary manslaughter of Katheryn Ferguson,” the U.S. Attorney’s Office said in a news release. Under federal law, voluntary manslaughter applies when someone kills another person “upon a sudden quarrel or heat of passion,” but without malice.

The judge ordered Aviles to serve seven years and three months in federal prison.

“We hope the sentence provides a measure of justice, however partial, for the loss of Katheryn Ferguson to her children and her family,” Acting U.S. Attorney Eric Heimann said in a statement.

While Friday represented the end of the federal case against Aviles, it didn’t end the investigation, as law enforcement personnel across multiple states are continuing to seek out evidence and search for Ferguson’s body.

“Definitely it doesn’t stop at this,” Park County Sheriff Darrell Steward said Friday.

The disappearance 

Ferguson went missing in early October, while she was traveling with Aviles and their two children. Aviles was supposed to bring Ferguson back to Cody from Arkansas, but only he and the children completed the trip. When Ferguson’s mother reported her as missing in early November, Aviles told Cody police that his girlfriend “was not missing” and simply didn’t want to speak to her mother, charging documents say.

Ferguson was last seen on Oct. 5 in Trumann, Arkansas, when a police officer checked on their vehicle and found her seated in the passenger seat of Aviles’ Dodge Durango; Aviles was in the driver’s seat, with the kids alongside.

However, when a Texas state trooper encountered the Durango several days later, Ferguson was gone and a piece of tape was visible on the passenger side door. Weeks later, personnel with the Park County Sheriff’s Office discovered that the tape was covering an apparent bullet hole. They found evidence that multiple shots had been fired inside the vehicle and recovered multiple bloodstained items; that included a fully loaded magazine for a .45 caliber Glock that had blood on the back.

Deputies found the Durango out in a remote part of Oregon Basin south of Cody, just two days after Cody police questioned Aviles about Ferguson’s whereabouts. The passenger seat that Ferguson was last seen sitting on had been removed, and deputies say they caught Aviles approaching the vehicle with a gas can in hand.

A few days later, on Nov. 8, Aviles preemptively turned himself in to the sheriff’s office and invoked his right to remain silent. He’s remained in custody since then.

Federal charges

The U.S. Attorney’s Office in Wyoming took on the case shortly after his arrest. Because Aviles had a prior felony conviction for possessing heroin in Cody in 2016, it was a federal crime for him to possess firearms or ammo.

Aviles’ trial was set for June in Cheyenne, but the parties reached a deal days before the start date: Aviles agreed to plead guilty and to not seek to suppress the evidence against him, while prosecutors agreed to seek no more than eight years of prison time and to drop a second count of illegally possessing a Glock model 41 handgun.

“They also agreed that this sentence does not preclude him [Aviles] from being charged with murder or manslaughter at a future date,” said Lori Hogan, a spokeswoman for the U.S. Attorney’s Office.

In the release, Heimann called the case “a sad reminder that felons cannot be trusted with firearms,” and said his office “will continue to aggressively prosecute gun crimes to help make the people of Wyoming safer.”

He described the sentence as the product of close cooperation between local, state and federal law enforcement officers and prosecutors. The release specifically mentioned work by the Park County Sheriff’s Office, the Wyoming Division of Criminal Investigation, the FBI and the Bureau of Alcohol, Tobacco, Firearms and Explosives.

An active investigation

In a spring court filing, Aviles’ court-appointed defense attorney indicated that authorities in another, unspecified state were getting close to deciding whether to charge Aviles in connection with Ferguson’s apparent homicide.

“... It is believed that a charging decision in that matter may occur in the coming weeks,” Assistant Federal Public Defender David Weiss wrote in March. Six months later, however, the case remains active.

Sheriff Steward said personnel from his office and other agencies have spent “hours and hours and hours” investigating Ferguson’s disappearance, with Investigator Clayton Creel “constantly working on stuff with all these different agencies, trying to resolve this.” He said law enforcement officials have narrowed their focus to a specific area, though it still spans multiple jurisdictions.

The 87-month sentence handed to Aviles last week “gives us breathing room to continue on,” Steward said, without needing to worry about the suspect being out of custody.

In a Sunday Facebook post, Ferguson’s mother Mona Hartling promised that “we will have Justice and peace for Katie and our family.”