The victim, a 16-year-old girl whose hair was cut mohawk style — where the sides of the head and shaved, leaving a central band of hair from front to back — survived.
Marianne Dahle, 26, is accused of tying up the teenage girl and cutting away a 6-by-8-inch (15- by 20-centimeter) section of her scalp with a four-inch (10-centimeter) knife. The incident took place on Jan. 18.
The teen spent two weeks in the hospital and is now recovering at home. Authorities did not release the girl's name, though she identified herself as Sheila to journalists.
Dahle faces a felony arrest warrant for aggravated battery. If convicted, she could be sentenced to 14 years in prison.
"When I say this gal was scalped, she was truly scalped," said Bill Braddock, chief deputy of Boise County. "The top of her head, her hair, was completely cut off. The motive, as near as we've been told by witnesses, was retaliation for acting in a way that the adult perceived as being offensive to women as a gender."
Dahle, the victim and another teenage girl who witnessed the attack were long-term acquaintances who formed a punk clique with its own rules, Braddock said.
"In their punk group, wearing a mohawk is a sign of being a punker, and according to their creed if you disrespect women you are not allowed to wear a mohawk," he said. Braddock did not say what the victim had supposedly done to disrespect women.
Sheila, who is from Nampa, near Boise, told Boise TV station KTVB that she thought the woman was going to cut her hair.
"Why would they do something like this to me?" Sheila asked. "I thought they were my friends."
Police were alerted after Dahle allegedly dropped the teen off at a Boise hospital. Authorities recovered the scalp, but doctors were unable to reattach it, Braddock said.