Kaitlin Armstrong, killer of elite cyclist, was lured to her arrest by U.S. marshals’ ad for a yoga instructor

Federal authorities planted a phony advertisement seeking a yoga instructor to capture the Texas woman later convicted of murdering an elite bicyclist and perceived romantic rival, officials said.

When detectives suspected that Kaitlin Armstrong, 36, was the person who murdered Moriah "Mo" Wilson, 25, their most daunting task was simply finding Armstrong, who had vanished from Austin, where the slaying occurred on May 11, 2022.

Tips eventually led authorities to Costa Rica, where Deputy U.S. Marshals Damien Fernandez and Emir Perez still had a needle-in-a-haystack challenge of finding their suspect in the tropical paradise filled with Americans living relaxed expat lives.

"We had other intelligence indicating that ... she was staying in hostels in Costa Rica," Perez told CBS' "48 Hours." "And I don’t know if you know anything about Costa Rica, but Costa Rica has a lot of hostels — a lot, an unbelievable amount of hostels."

They found a businessman with connections to Armstrong, who was now going by the name "Beth" and, according to pictures provided by the contact, had changed her appearance.

And even when the search narrowed to the small mountain town of Santa Teresa, it was still a tough search.

"I think from the get-go we were told ... you’re going to be in for a surprise, ’cause a lot of the women in Santa Teresa look just like Kaitlin — a lot of them," Fernandez told the CBS News show.

With little hope of finding Armstrong, authorities threw a Hail Mary pass.

“We decided we were going to put an ad out ... or multiple ads for a yoga instructor and see what would happen,” Perez told “48 Hours."

It paid off.

"We got a bite, somebody that, um, identified herself ... as a yoga instructor and said they wanted to meet with us at a particular hostel ... and we said ... 'this is, this is our chance!'" Perez told "48 Hours."

Perez met Armstrong and got close enough to see bandages on her face, which were later connected to cosmetic surgery she had had, allegedly to change her appearance and evade capture.

Still, the changes weren't enough to throw Perez off the trail.

"The eyes are the exact same ones that I saw in the picture," he said, according to the news show. "And this is her 100%."

Fernandez said of his partner, "He gets in the car, and he is like, 'That’s her. She’s in there.'"

Local police moved in for the arrest, and receipts were later found at Armstrong's hostel, showing payments for plastic surgery, officials said.

A Travis County jury convicted Armstrong of murder on Nov. 16. She was sentenced to 90 years in prison the next day.

Armstrong's attorney couldn't immediately be reached for comment Monday.

This article was originally published on NBCNews.com