31-Year-Old Poses as H.S. Student

V A N C O U V E R, Wash., April, 12 -- Brianna Stewart had everyone fooled. For years she posed as a teenager, attending proms, playing tennis, and even graduating from Evergreen High School last spring.

Even her boyfriend of more than one year didn't know the apparent truth — that she was a 31-year-old passing herself off as a teenager.

"I was in love for the first time," Kerry Dunn told Good Morning America. "And, you know, it was wonderful to me. But it turned out to be one big illusion."

Tall Tales, Tough Consequences

Authorities say the girl who posed as an unfortunate teen in blue bib overalls and tennis shoes was actually an adult named Treva Throneberry.

Calling herself "Brianna," Throneberry strolled into Vancouver more than three years ago, claiming she was homeless.

One of the guardians who provided temporary homes for Throneberry told ABCNEWS she claimed to have survived life in a cult, and later, life on the streets.

"She said her mother was murdered in the coven," recalled former guardian Randy Fisher, "That she never knew who her real father was, except she had a name and his name was Michael Stewart and he lived in Portland."

Her lies caused a few problems for those that came to know "Brianna" over the years. They got one Washington state man in trouble with the law.

A former male acquaintance of hers was charged with having sex with a minor after he became intimate with the high school sophomore. He will now have his name cleared, since she was actually 28 at the time of their encounter.

A Trail of Deception

But Vancouver residents weren't the only ones fooled by Throneberry.

In Altoona, Pa. she was known as "Stephanie Daneille Lewis." In 1996 she attended a Texas high school under the name of "Emily Kara Williams;" she was 27 at the time.

Today, Throneberry faces charges of first- and second-degree theft and perjury.

She is accused of defrauding the Washington State Department of Social and Health Sciences of $3,620.27 that was paid for her foster care. She also is accused of defrauding Clark College out of $1,050 in tuition that was waived after she claimed to be a homeless teen.

The perjury charge alleges she illegally obtained a state identity card under the name "Brianna Stewart."

Police discovered the girl's true identity after she provided fingerprints in exchange for a birth certificate under the name "Brianna Stewart." Those prints revealed the woman's strange and confusing past.

Throneberry's parents confirmed her true identity when police sent them a picture of her.

But even as she sits in a county jail awaiting a May 23 trial, Throneberry continues to claim she is "Brianna Stewart."

The woman's defense attorney plans to seek a mental evaluation before the trial.