NBC -- Nancy Salas told Glendale, California police Thursday that a kidnapper did not abduct her and that she made the whole story up.
Authorities said she was apparently embarrassed that she would be unable to produce a diploma at a graduation party planned for next month.
"She told detectives she was idolized by her family and friends, and one story led to another," Glendale police Sgt. Tom Lorenz said late Thursday.
Around 11 a.m. Thursday, Salas walked into a Merced, California store and said she was abducted at knifepoint.
She asked the store clerk to call 911.
Salas was about 275 miles away from home.
Glendale police flew to Merced and returned Salas to their police station for a lengthy interview.
Around 9 p.m., Salas was released to family waiting outside the police station.
Salas whispered to a reporter that the pressure of a "double life" caused her to run away.
Merced and Fresno County authorities will determine if Salas will be charged with filing a false police report, Lorenz said.
The 22-year-old woman went missing Wednesday morning after going on what her parents called a "routine" jog.
Glendale police believed the worst and launched a large search for Salas.
A police helicopter and bloodhound were used as well as dozens of peace officers.
There was an initial report Salas was a UCLA student about to graduate --
but as the disappearance became a larger mystery -- it was revealed she had not been enrolled since 2008.
"There's obviously a deception," Lorenz told the LA Times on Thursday morning. "I don't want to go so far as to call it a double life. "We have a home life, and then we have our personal life. We've all been there."
It was unclear exactly what Salas did between Wednesday morning and the time she walked into United Floor Covering in Merced and had an employee dial 911.
Lorenz said Glendale police would not seek to recover any police costs from the family.
"She's an adult," he said. "She's free to come and go as she pleases. Her family reported her missing, believing something was wrong. She belongs to a close and loving family, circle of friends and church community."
The family would not comment Thursday night outside the police station.
Salas is in good health and did not appear injured.