A new federal warrant puts an end to speculation about whether police believe they recovered the gun used to kill Moriah "Mo" Wilson in the home of her suspected love-triangle killer Kaitlin Armstrong in Austin last month.

The U.S. Marshals announced earlier Thursday that the 34-year-old Armstrong, who is already wanted on a Texas murder warrant, now faces a federal charge of unlawful flight to avoid prosecution.

The new warrant confirms that spent shell casings at the murder scene match those that police later fired from a handgun seized at Armstrong’s home, which she shared with her boyfriend Colin Strickland, 35, another professional cyclist who had gone out to dinner with the 25-year-old Wilson the night of the shooting.

"On the date of the murder, Armstrong owned a pistol that APD (Austin police) seized from Armstrong’s residence in the course of their investigation," the new complaint reads. "Laboratory test-firing of Armstrong’s pistol confirmed that it fired the spent shell casings that APD found at the scene of the murder."

KAITLIN ARMSTRONG: SUSPECT ACCUSED IN TEXAS LOVE TRIANGLE MURDER SOLD CAR FOR $12,200 BEFORE FLEEING, FEDS SAY

Anyone with information on Armstrong’s whereabouts is urged to contact the U.S. Marshals Service Communications Center at 1-800-336-0102

Left: victim Moriah "Mo" Wilson after a race. Right: A photo of suspect Kaitlin Armstrong released by the US Marshals. (The Wilson Family/US Marshals)

Police had previously said of the recovered weapon that "the potential that the same firearm was involved is significant."

Strickland and Armstrong were living together, and according to an earlier affidavit, he bought her the gun at the start of the year.

Shortly after Strickland dropped off Wilson on the night of her death, police alleged in the murder warrant, Armstrong’s Jeep SUV appeared on a neighbor’s security camera.

Kaitlin Armstrong

U.S. Marshals are searching for Kaitlin Marie Armstrong, who is wanted for the May 11 murder of Moriah "Mo" Wilson. (US Marshals)

FUGITIVE KAITLIN ARMSTRONG: TIMELINE OF AUSTIN MURDER SUSPECT'S DISAPPEARANCE

"I respectfully submit that there is probably cause to believe Armstrong has fled the State of Texas in order to avoid prosecution for the crime of murder," Deputy Marshal Emir Perez wrote in an affidavit. The warrant was filed on May 25 but was unveiled Thursday.

Police say Armstrong fled Texas last month and flew to New York, where a witness told Fox News Digital she visited her sister before last being seen at Newark International Airport just across the New Jersey state line.

READ THE FEDERAL COMPLAINT

The trail goes cold from there, according to Deputy Marshal Brandon Filla, but investigators are hoping the increased reward of $21,000 leads to more tips as they continue the manhunt.

KAITLIN ARMSTRONG MANHUNT: NEW YORK CAMPSITE LINKED TO SUSPECT IN AUSTIN CYCLIST LOVE TRIANGLE SLAYING

Colin Strickland standing outside

Colin Strickland seen outside his Austin, Texas, home on June 17, 2022. (MEGA)

Jason Jensen, a Utah-based private investigator who has taken an interest in the case, said a vehicle history report shows the Jeep that Marshals say Armstrong sold for $12,200 before fleeing Texas was worth more than $16,000 – a striking discount in a market where vehicle prices have skyrocketed.

"The quick sale manifests her intent to run," Jensen told Fox News Digital Thursday. "She was ditching the car, likely knowing officials could trace to whereabouts through her plates."

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Cash on hand would be "more useful" to someone fleeing prosecution than a vehicle police were likely looking for, he added.

Armstrong sold the vehicle to an Austin CarMax dealership on May 13 – one day after she was questioned and released by Texas authorities, the Marshals revealed Thursday morning.