It's a puzzling case; a flight attendant showing up for work at New York's LaGuardia airport on the morning of January 14, 2016 in her blue uniform. But instead of hopping on a flight, she handed in her equipment and quit. She then walked out on foot. That was the last time anyone saw Sierra Shields.
"Right now, it's difficult to see what happened when she left the terminal," Chris Shields, Sierra's father, told Dateline. "It's a real mystery at this point, but we can't give up."
Flyers with Sierra's photo are posted throughout the city. This past weekend's historic snow storm and the cold conditions created even more of a worry for her family, who simply hope Sierra is somewhere warm. Chris keeps revisiting the last time he spoke with his daughter, and says her demeanor that morning is weighing heavily on him.
"When we spoke with her that morning, she seemed pretty preoccupied -- distracted. Something was on her mind," Chris told Dateline. "Then we got disconnected, which is out of character, as anyone who knows Sierra would tell you: She doesn't hang up on anyone, not even telemarketers."
Neither of her two roommates has seen or heard from her. Inside their apartment, Sierra left her phone and wallet. Nothing else appeared to be missing.
Sierra is a flight attendant for Shuttle America and works on flights for Delta and United Airlines. She was working hard to reach several goals this year, while she wasn't up in the air, including launching a website about the importance of loving others. A resident of Astoria, Queens, Sierra is a devout part of the Connection Church, and has formed very close relationships with other members.
It's clear from the outpouring of social media postings she is very much missed.
"It comes out through the slew of people and postings about her," said Chris. "You can't help but to love her, because of the love she had for you."
The New York Police Department is investigating, but officials say they cannot release much information as it is an ongoing case.
While law enforcement follows up on reported leads, Sierra's family is doing what they can to help. Her mother and father flew in from their home outside Chicago and have been offered housing from members of Sierra's church. All of Sierra's four siblings were in town over the weekend, and several remain in town this week.
Social media is also abuzz. The family started the Facebook page 'Find Sierra Shields' shortly after she disappeared. The page has garnered more than 9,000 likes since it was opened. Many also share digital fliers and photos of Sierra on twitter using the hashtag #FindSierraNYC.
"The more people who see her photo, the better," said Chris. "No one really knows what may have happened to her. And if the right person sees it and recognizes her, we could get her home safely. We will find her. Our family has faith in that."
Sierra Shields is described as 5'6" tall, weighing 160 lbs. with black hair and brown eyes.
If you have any information regarding Sierra, you're asked to call the New York Police Department Crime Stoppers at (800) 577-TIPS, or text tips to 274637 then enter TIPS577.