Bianca Noel Piper was born on December 26, 1991, in Foley, Missouri. As a child she was hospitalized for ADHD and severe bipolar disorder and required daily medication to prevent disorientation and hallucinations. At the time of her disappearance she was in eighth grade at Winfield Middle School, enrolled in special education classes due to a short attention span and repeated absences. Her therapist had recommended that her mother drive her a distance from home and let her walk back alone, as a way to help her manage her own aggression.
On the evening of March 10, 2005, Piper and her mother argued over doing dinner dishes. Despite snow that night, Piper — who had found the walking exercise helpful — asked to do it again, requesting to be dropped off farther from home than before. She was last seen around 6:15 p.m. when her mother left her at McIntosh Hill Road in Foley, roughly one mile from their home. She was wearing a lime-green blouse, a gray Adidas hooded sweatshirt, blue jeans, and white tennis sneakers, and was carrying a flashlight. When she had not returned home hours later, her mother reported her missing at 8:20 p.m.
Investigators initially believed Piper had gotten lost, but after an extensive search using horseback riders, four-wheelers, and search dogs conducted by the Lincoln County Sheriff's Department, authorities came to believe she had been abducted. Piper had no history of running away. Her mother and her mother's live-in boyfriend both passed polygraph tests, and her biological father was extensively interviewed; no family member is considered a suspect.
In 2007, a multi-jurisdictional task force examined a possible connection between Piper's disappearance and Michael J. Devlin, following the discovery of two other missing Missouri teenagers, Shawn Hornbeck and Ben Ownby, alive in Devlin's apartment. The task force also reviewed possible links to the earlier disappearances of Scott Allen Kleeschulte (1988) and Charles Arlin Henderson (1991). A Lincoln County detective stated a belief that Devlin was at least aware of the search for Piper. The task force was dissolved in October 2007 after finding no evidence connecting Devlin to Piper's case or the others.
In February 2023, investigators drained a septic tank near where Piper was last seen, and the Lincoln County Sheriff's Department began working with forensic genealogy company Othram in an effort to advance the case. Piper's father died in 2009; her mother lives in St. Charles, Missouri. The case remains open but is considered cold, and is one of two active missing-person cases in Lincoln County, alongside that of Charles Arlin Henderson. As of January 2026, the Amber Alert issued for Piper remained active.