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.

Traveling alone

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.