When Ken Dunn met Brianna Stewart in a math class during his sophomore year, he thought she seemed a little old. "I thought she was a teacher at first," he said. "But then she told me she was my age, so I believed her." After that, Ken never once suspected that she was actually a 31-year-old woman faking her way through high school--a woman who now sits in jail on charges of perjury and fraud.

"I was so charmed by her," he said. "Here was this girl, who'd come off the street, gotten off drugs so fast, and cleaned up. I really looked up to her." A lot of other people believed her story as well: foster parents, friends, and churches. For five years, between the ages of 27 and 31, Brianna couch-surfed and lived with anyone who would take her in while attending high school in Vancouver, Washington. That is, until last month, when she was arrested.

Brianna gave her fingerprints to the police in order to secure a social security card, and her prints matched those of 31-year-old Treva Throneberry, a woman who had turned up in legal trouble all over the country. In the seven years previous, she'd been to Idaho, Texas, North Carolina, and Pennsylvania. Finally, she'd stopped in Vancouver where her past--or as she claims, the past of another woman--caught up with her. Detective Smith arrested her on March 22 for charges of fraud and perjury, claiming she cheated the state out approximately $11,500 spent on her education and foster care.

After speaking with her from prison, it's clear she absolutely believes she's Brianna Stewart. "I'm not sure why I'm in prison, because I do believe I am Brianna Stewart," she told me. "I don't believe I'm this Treva person. I mean, I went to high school, graduated, and went to Clark College. I'm a normal person. I like to go to the mall, to play softball." Though this duality may sound unusual, according to Claire Holzman, a clinical psychologist who specializes in sexual abuse, Brianna's sincerity could be completely honest.

Though Holzman made it clear that there is absolutely no way to be sure about Brianna's condition, she suggested several possibilities, one of which is that Brianna could have Dissociative Identity Disorder, a common condition in people who were sexually abused as children. (According to several of her former acquaintences Brianna has, at times, claimed she suffered from extensive sexual abuse during her youth.) People who have this condition often create several personalities to deal with sexual abuse--one personality functions in everyday life, the other suffers the abuse.

If Brianna indeed has this disorder or a similar one, it's entirely possible she could be convinced of her story, inconsistencies and all. Even in 1997, when she accused Charles Blankenship of communicating with a minor (she was actually 28 at the time, he 47) she may have genuinely thought she was 17 at the time of the abuse.

If this is the case--or even if it's not--the question remains: How did she manage to slip through the Vancouver school and foster care systems without anyone noticing a mentally disturbed person, and more importantly, why is she being punished for the state's irresponsibility in noticing her health? "We don't do background checks on our students," says Carol Fenstermecher, spokesperson for Evergreen High School. Likewise, there were insufficient mental health services provided through the Clark County foster care services, a system she went in and out of for the five years she was there.

Brianna's lawyer says she will request a mental evaluation for her client. However, Treva/Brianna is not eligible to receive any psychological treatment for the duration of her time in jail.