Kaitlin Armstrong: Texas fugitive used aliases until Costa Rica cops detained her on immigration charge

Kaitlin Marie Armstrong is accused of gunning down gravel cycling pro and romantic rival Anna Moriah 'Mo' Wilson

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Kaitlin Armstrong, the Texas woman accused of a love triangle murder before fleeing to Costa Rica, was initially detained by Costa Rican authorities on a fraudulent passport charge before they discovered her true identity, authorities said Thursday.

Costa Rican officials initially apprehended the fugitive on the immigration charge on June 29, said Deputy U.S. Marshal Brandon Filla, the public affairs officer for the Marshals’ Austin Division.

The captured fugitive allegedly stalked and killed gravel cycling pro Anna Moriah "Mo" Wilson, 25, after the latter spent a night out with Colin Strickland, Armstrong’s 35-year-old boyfriend and also a pro cyclist. The two had a romantic history that angered the suspected killer, according to a police affidavit.

Filla likened Armstrong to "the worst of the worst criminals that wreak havoc on our communities" and noted that the Marshals-led fugitive task force had arrested the Austin serial bomber in 2018 and the Sixth Street shooting suspect last summer.

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Booking photos taken after Kaitlin Armstrong's extradition to the U.S. appear to show a change in her facial features. 

Booking photos taken after Kaitlin Armstrong's extradition to the U.S. appear to show a change in her facial features.  (US Marshals, Travis County Sheriff's Office)

Filla said a confidential source told Marshals that Armstrong had been transported to Newark Liberty International Airport in New Jersey – where authorities have said she was dropped off on May 18.

Federal law enforcement agents from Homeland Securities Investigations discovered that Armstrong flew to Costa Rica using a passport of "someone that was closely associated with her," Filla said, without divulging the owner’s name. Fox News Digital has reported that Armstrong was seen at a New York campground where her sister was living between her arrival in the Empire State and her flight out of the country.

"She took a bus from the San Jose airport in Costa Rica, hours away," Filla said, before police there tracked her route with "old-fashioned police work."

In Costa Rica, she used aliases including Beth Martin, Liz and Ari Martin, Filla said. She gave a fake name to police in an interview at Don Jon’s Hostel in Santa Teresa Beach, on the Pacific Ocean. They detained her on an immigration violation for the alleged fraudulent use of a passport. She eventually "confessed her true identity," Filla said.

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

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)

She claimed to Costa Rican officials that she didn’t have a key to a lockbox where she had her belongings, Filla said, and the hostel's owner was not around at the time of her arrest.

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"So she was taken into custody where she was taken away from the scene," Filla said.

Reporters subsequently got in touch with the hostel owner, who unlocked the box and found a purported receipt for plastic surgery and two passports – one belonging to Armstrong and the other to her sister.

Filla addressed the receipt but said he could not confirm its validity and noted that it did not have her name on it. The clinic named on the document told Fox News Digital it could not confirm Armstrong had ever been there.

However, Filla acknowledged that police found her with a bandage on her face, which she attributed to a surfing accident. Her booking photos also appear to show a change in her facial features.

A photo combination of a U.S. Marshal handout of Kaitlin Armstrong and her booking photo after her extradition to the U.S. from Costa Rica. 

A photo combination of a U.S. Marshal handout of Kaitlin Armstrong and her booking photo after her extradition to the U.S. from Costa Rica.  (U.S. Marshals/Harris County Sheriff's Office)

He credited three task force members by name: Deputy U.S. Marshal Emir Perez and Officers Jonathan Reilly and Mark McCloud. They and other investigators "forfeited their leave, their weekends and their holidays" in the 43-day manhunt.

Their perseverance led to Armstrong's ultimate capture at a beachfront hostel in Santa Teresa, a surfers’ paradise on the Pacific Ocean known for its waves, expat yoga community and jungle backpacking trails.

She had also altered her appearance, Filla said.

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She arrived back in the U.S. over the weekend and was transferred to Austin to face justice.

Armstrong faces charges of first-degree murder and unlawful flight to avoid prosecution in connection with Wilson’s death, as well as an unrelated theft of services misdemeanor for allegedly walking out on a Botox bill in 2018.

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

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

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Filla also credited media coverage for helping to generate 80 tips that helped investigators catch the suspect.