A Northern California mother of two has been sentenced to 18 months in prison for faking her own kidnapping so she could go back to a former boyfriend, which led to a three-week, multi-state search before she resurfaced on Thanksgiving Day in 2016.

Sherri Papini, 40, pleaded guilty last spring under a plea bargain that requires her to pay more than US$300,000 in restitution.

Probation officers and Papini's attorney had recommended that she spend a month in custody and seven months in supervised home detention. But senior US District Judge William Shubb said he opted for an 18-month sentence in order to deter others.

The judge in the case, which echoed the plot of Hollywood film Gone Girl, said he considered the seriousness of the offence and "the sheer number of people who were impacted".

Papini, who was emotional throughout the proceedings, quietly answered "Yes, sir" when the judge asked if she understood the sentence. Previously she was in tears as she gave a statement to the court accepting responsibility and admitting her guilt.

"As painful as it is," Papini accepts her sentence as part of her recovery, defence attorney William Portanova said after the hearing.

Portanova previously said Papini was troubled and disgraced and that she should serve most of her sentence at home. Prosecutors, though, said it was imperative that she spend her full term in prison. The judge ordered her to report to prison on November 8.

Sherri Papini of Redding with her attorney William Portanova. Photo / AP

"Papini's kidnapping hoax was deliberate, well planned and sophisticated," prosecutors wrote in their court filing. And she was still falsely telling people she was kidnapped months after she pleaded guilty in April to staging the abduction and lying to the FBI about it, they wrote.

"The nation is watching the outcome of Papini's sentencing hearing," Assistant US Attorneys Veronica Alegria and Shelley Weger wrote. "The public needs to know that there will be more than a slap on the wrist for committing financial fraud and making false statements to law enforcement, particularly when those false statements result in the expenditure of substantial resources and implicate innocent people."

"Outwardly sweet and loving, yet capable of intense deceit ... Ms Papini's chameleonic personalities drove her to simultaneously crave family security and the freedom of youth," Portanova wrote in his responding court filing.

So "in pursuit of a non-sensical fantasy," Portanova said the married mother fled to a former boyfriend in Southern California, nearly 1000km south of her home in Redding. He dropped her off along Interstate 5 about 240km from her home after she said she wanted to go home.

Passersby found her with bindings on her body, a swollen nose, a blurred "brand" on her right shoulder, bruises and rashes across her body, ligature marks on her wrists and ankles, and burns on her left forearm. All of the injuries were self-inflicted and were designed to substantiate her story that she had been abducted at gunpoint by two Hispanic women while she was out for a run.

The wounds were a manifestation of her "unsettled masochism" and "self-inflicted penance", Portanova wrote. And once she began, "each lie demanded another lie.

Prosecutors said Papini's ruse harmed more than just herself and her family. "An entire community believed the hoax and lived in fear that Hispanic women were roving the streets to abduct and sell women," they wrote.

Prosecutors agreed to seek a sentence on the low end of the sentencing range in exchange for Papini's guilty plea. That was projected to be between eight and 14 months in custody, down from the maximum 25 years for the two charges.

She has offered no rationale for her actions, which stumped even independent mental health experts who said her actions didn't conform with any typical diagnosis.

"Papini's painful early years twisted and froze her in myriad ways," Portanova said in arguing for home confinement. With her deception finally revealed, he said, "It is hard to imagine a more brutal public revelation of a person's broken inner self. At this point, the punishment is already intense and feels like a life sentence."

But prosecutors said her "past trauma and mental health issues alone cannot account for all of her actions".

"Papini's planning of her hoax kidnapping was meticulous and began months in advance - it was not merely the reaction to a traumatic childhood," they wrote.

After her arrest in March, Papini received more than US$30,000 worth of psychiatric care for anxiety, depression and post-traumatic stress disorder. She billed the state's victim compensation fund for the treatment, and now must pay it back as part of her restitution.

As part of the plea agreement, she has agreed to reimburse law enforcement agencies more than US$150,000 for the costs of the search for her and her nonexistent kidnappers, and repay the US$128,000 she received in disability payments since her return.