- A feed of photos on Instagram marks Sierra's trail then goes cold
- She flew to Istanbul alone after making friends there online
- The mother of two hasn't been heard from since January 21 and didn't fly home the next day
- Her husband, Steven, says he has no explanation as to what happened to her
Sarai Sierra followed her passion to Istanbul -- a budding photographer lured by the possibilities the picturesque, ancient city has to offer.
But the day before she was supposed to fly back home, the 33-year-old mother of two went missing.
Sierra had taken up photography last year, posting her work to the photo sharing app Instagram and quickly amassing 3,000 followers.
Some people she met through the service encouraged her to visit Istanbul, her husband, Steven, said. They offered to act as tour guides, he said.
"You're admiring pictures, but you're getting acquainted with people that you've never met before," the husband said.
He thought the trip was a great idea for his wife.
Now, he can't help but wonder whether she should have trusted people she met online.
Sierra had originally planned to travel with a friend, who canceled, her husband said.
She flew alone to Istanbul on January 7.
"She did a lot of researching about the area, about where she was going to stay, the safest places to go and the time of day to travel," her friend Magalena Rodriguez said.
After her arrival, she began posting pictures to Instagram and stayed in touch with family back home via Skype.
Her photo feed displayed images of Istanbul's beautiful skyline and historic landmarks.
She also squeezed in an excursion to Amsterdam in the Netherlands and to Germany, starting January 15, where she went to photograph graffiti.
She returned to Istanbul on January 19.
Three days later all signs of life from Sierra ceased.
No-show on flight home
Sierra had rebooked her flight to arrive back early, on January 22, in part to surprise her two sons, 9 and 11.
Just days before her scheduled trip home, Sierra spoke with her father David Jimenez via Skype to remind him of her flight number and arrival time.
On January 21, she messaged her sister to say she was glad to be heading back to New York.
When Jimenez went to Newark airport to pick Sierra up, she didn't show, he said.
The airline told him she had never checked in for the flight.
"She kept in contact with us all the time," Sierra's mother, Betzaida Jimenez, said. "And then not to hear from her? It's not like her."
On Monday, Steven Sierra landed in Istanbul with his wife's brother to help police search for her.
The next day, police released a surveillance camera video of Sarai at a shopping mall, flipping through her iPad.
The scenes from January 20 are the last known images of her.
Last signs of life
The manager of the small private hotel where Sierra was staying reported last seeing her the day the surveillance video was shot. That was a Sunday.
Her Skype account, which she avidly used, went silent a day later. A day after that was when she missed her flight home.
The time she last talked with her family, Sierra was planning to see the Galata Bridge and visit the Asian side of Istanbul, her husband said.
The former capital of the Byzantine and East Roman empires straddles the continents of Europe and Asia.
After her family raised the alarm that she was missing, some of her belongings -- including her passport and medical cards -- were found in her room in Istanbul, though her iPhone and iPad were not there, according to her husband.
A heartbroken family
Her parents can't watch the surveillance video. It's too painful.
"I wish she was close, wish she was close by, so I could reach out and grab her and bring her back," her father said.
Steven Sierra has lost his appetite for living and sometimes wishes that one morning he just wouldn't wake up.
But he has to keep going for the sake of his children.
"I would never wish this on anybody," he said. "There's times when...you feel like you're gonna lose it mentally."
He says he wants to be there to protect her, wants to make sure she is not cold or hungry.
But all he can do is wait. And hope.