US Marshals Reveal Facebook Ad Led to Capture of Woman Who Killed Boyfriend's Former Lover

On Sunday's 48 Hours, U.S. Marshals revealed how they eventually caught Armstrong about a month and a half after she went on the run to Costa Rica, following the murder of pro cyclist Anna "Mo" Wilson.

Wilson was found bleeding and unconscious at a friend's home in Austin, after traveling there for a local race, on May 11, 2022. She was pronounced dead on the scene.

After Wilson's death was ruled a homicide, Armstrong was briefly detained by police -- before being released due to an invalid warrant. The next day, she reportedly sold her Jeep Grand Cherokee -- which was seen in surveillance footage near where Wilson was killed the night of the murders -- before hopping onto a flight to the East Coast. Per the U.S. Marshals, she then used a fraudulent passport to catch another plane from Newark to San Jose, Costa Rica on May 18 -- the day after Austin P.D. issued a homicide warrant for her arrest.

According to U.S. Marshal Damien Fernandez on 48 Hours, authorities had a hard time finding Armstrong in Santa Teresa, Costa Rica -- and were told from the get-go, "a lot of women in Santa Teresa look just like Kaitlin... a lot of them."

Knowing she was a yoga instructor and enthusiast, investigators even had a female operative take local classes, hoping to track her down.

"We made friends with people there that would send us pictures, 'I think I saw her at this restaurant yesterday,' and she's in the back in the background of a photo that I took, stuff like that," Fernandez explained.

Finally, they broke the case wide open when they decided to place an ad for a yoga instructor on a local Facebook page "just saying, hey, we're at this hostel, we're looking for a yoga instructor as soon as possible. Please contact us at this number," said Fernandez.

They didn't immediately get any responses, but just as they were ready to head home, they "got a bite" from someone claiming to be an instructor. After authorities then got a better look at the woman who responded at a hostel, they confirmed she was Armstrong and arrested her.

She was apprehended at a hostel in Santa Teresa Beach in Provincia de Puntarenas, before being returned to the States. Armstrong reportedly had a nose job in that time and had also dyed her hair brunette.

Her case was dubbed a "love triangle" after it was discovered Wilson briefly dated Armstrong's boyfriend, 35-year-old professional cyclist, Colin Strickland, while the two were on a break.

During her trial, prosecutors played up the love triangle bit, saying Armstrong shot Wilson in a jealous rage, hitting both her head and heart. They also claimed she tracked Wilson's location with a fitness app used to keep track of her rides.

Armstrong's attorney, however, said she had been unfairly portrayed as "a jealous psycho." As for why she made a run for it, he argued she was "scared" of the investigation and the actual killer -- suggesting someone else could have killed Wilson.

She was found guilty last November and sentenced to 90 years in prison.