The girl's father was convicted earlier this year of sexually abusing the teen. He was sentenced in September to six years in prison after pleading guilty to several crimes, including incest.
The victim, now an adult, told authorities that she was abused from 2006 until she left for college in 2010.
Snohomish County authorities filed a complaint with the state Department of Health against the therapist after learning she had suggested that the parents and the girl, then 15, sleep in one bed as a way to bond.
The Herald is not naming the therapist because no formal action has been taken against her license and she hasn't been charged with a crime.
The girl and her adoptive parents started seeing the therapist to address the girl's "abandonment and attachment issues," court papers said.
The teen had been in foster care after spending most of her childhood in a polygamous clan in Utah, where she was abused. She met the Snohomish couple soon after she was taken away from her birth parents.
The girl told authorities that a month after the therapist suggested she sleep in the same bed with her new family, her adoptive father began sexually assaulting her.
The victim told investigators that she was forced to have sex with him every week. When she attempted to resist, she said he threatened to send her back to her birth parents. He warned her that she would be married off into a polygamous family.
During their investigation, detectives interviewed the therapist, who confirmed that she'd suggested "attachment therapy," court papers said.
State health officials have wrapped up the investigation into the complaint. Lawyers are reviewing the probe to determine whether any action should be taken against the therapist's license, said Donn Moyer, a spokesman for the state Department of Health.
The department has authority to revoke or suspend a health care provider's license.
Diana Hefley: 425-339-3463; email@example.com.
More Local News Headlines
Everett City Council puts courthouse deal on hold over parking questions Monroe skatepark will undergo $240,000 worth of improvements GPS coming to most local police, fire vehicles Locals fondly recall author Ann Rule Man sought in Marysville shooting Voters to decide on Marysville fireworks ban Life in prison for killer of Seattle police officer who was from Marysville Volunteer brings troubled felines to inmates, who help tame them
Our new comment system is not supported in IE 7. Please upgrade your browser here.