PORTLAND, Ore. (KOIN) — “I think one of the things I really liked about my sister the most is how bubbly and giddy she could be.”

Mona Dotson hasn’t seen her sister Tiffany Bettis in more than 3 years. Tiffany — who also was known as Melinda Smith — was living in both Fairview and Roseburg at the time. She was last seen at the Quality Inn in Gresham on March 2, 2015.

Dotson said the most difficult part of these past 3 years has been the “ambiguity.”

“You don’t know where she is, you don’t know if she’s OK, so that’s difficult.”

She left behind 3 elementary-age children and many people have told investigators they don’t believe she would have left her children willingly. Investigators say foul play has not been ruled out in her disappearance.

The family has offered a $10,000 reward for information leading to an arrest and conviction. Crime Stoppers of Oregon also offers up to $2500 for an arrest in an unsolved felony crime.

An undated family photo of Tiffany Bettis, provided June 21, 2018 (Courtesy)

“My sister would often say that she would never leave her kids. Her kids mean the most to her,” Dotson told KOIN 6 News. “She would often say that I would never leave my kids. So for her to go missing, for her to leave on her own accord, that doesn’t make sense to me at all. It doesn’t sit right with me. And I know that was some of the initial, well, she just left, ran away — I don’t see that.”

Ttiffany Bettis bought a house in Fairview in the early 2000s. Dotson said she remembered her sister being so happy she was a homeowner.

“Then later, when she met her husband, they also had a home in Roseburg. That was their primary residence,” Dotson said. “Then when she would come up to visit family, they would stay at the house in Fairview.”

She hopes neighbors in Fairview or in Roseburg could call authorities if they saw something, anything, out of the ordinary.

Finding out what happened would mean a lot to the family. “I mean, my mom and I, we miss my sister.”

“I think like anybody you ever interview on the news, they just want their family back,” Dotson said. “I think my fear is just that she’s not coming back.”