US Marshals detail hunt for murder suspect Kaitlin Armstrong in Costa Rica

Kaitlin Armstrong, a suspect in the murder of professional cyclist Anna Moriah Wilson, changed her appearance and used several aliases after fleeing to Costa Rica, federal authorities said Thursday.

Armstrong, 34, was arrested on June 29 at a hostel on Santa Teresa Beach in Provincia de Puntarenas after a 43-day search, according to the U.S. Marshals Service. She has since been deported and returned to the U.S., where she was booked on Tuesday in Travis County Jail by the Austin Police Department.

Armstrong was charged with felony first-degree murder in connection with the fatal shooting of Wilson, 25, in Austin on May 11. Wilson was romantically linked to Armstrong's boyfriend, professional cyclist Colin Strickland, and was found shot hours after meeting up with him, police said.

Days after being questioned by police about the incident, Armstrong, a yoga instructor and realtor, fled Austin, authorities said.

During a press briefing Thursday, authorities detailed the hunt for the fugitive, which had been upgraded to "major case status" by the U.S. Marshals.

Investigators learned through a confidential source that the suspect was provided transportation to Newark Liberty International Airport on May 18, a day after Austin police officers issued a homicide warrant for her arrest, the U.S. Marshals said. She boarded a flight that day to San Jose, Costa Rica, using a fraudulent passport, according to Deputy U.S. Marshal Brandon Filla.

Armstrong "presented a passport that did not belong to her but belonged to someone that was closely associated with her," Filla told reporters during a briefing Thursday.

Upon arriving in Costa Rica, Armstrong used several different aliases, including the name Beth Martin, at various lodgings and yoga studios, according to Filla.

"She was really trying to build something where she could instruct yoga there in Costa Rica," Filla said.

Investigators went door-to-door, tracking Armstrong "from yoga establishment to other yoga estalishments" and spoke to lodgings that she had "left behind" as they closed in on her, Filla said.

Authorities eventually detained Armstrong at the Don Jon's hostel on Santa Teresa Beach on an immigration violation for the fraudulent use of a passport, and she was transported back to San Jose, Filla said. During the six-hour drive she "eventually confessed to her true identity," Filla said.

Armstrong had altered her physical appearance -- dying her long, light brown hair a darker shade of brown and cropping it to shoulder length -- and had a bandage on her nose, according to Filla.

When asked if they believe that Armstrong may have obtained plastic surgery, Filla said they have been unable to confirm that at this time.

"I will say, she had a bandage on her nose with a little bit of discoloration under her eyes," he said. "Her statement was that it came from a surfboard incident, and I think we'll just leave it at that."

Filla said authorities are investigating the use of the fraudulent passport and won't be commenting further at this time on any assistance they believe she had.

Authorities were offering a combined $21,000 for any tips leading to Armstrong's arrest and received over 80 tips nationwide, Filla said.

Armstrong is currently being held at Travis County Jail on a $3.5 million bond. A hearing in a Travis County criminal court has been scheduled for July 20, court records show.

Armstrong's attorney, Rick Cofer, said in a statement Saturday that "neither Kaitlin nor her attorneys will be making any statements to the media at this time."

Following Thursday's briefing, Strickland said he was "grateful that investigators, including the U.S. Marshals, have pursued all leads and opened the path to justice for Moriah Wilson and her family."

"I will continue to provide my full cooperation for the sake of the Wilson family as they, along with so many others who have been affected, endure the burden of this senseless tragedy," he said in a statement.

ABC News' Lisa Sivertsen contributed to this report.