An American serial killer profiler believes kidnapped Californian mother Sherri Papini is lying about her abductors, and that her ordeal "has serial rapist, serial killer" written all over it.

John Kelly said Mrs Papini's story of being abducted by two Hispanic women didn't sound likely, and that she is probably lying about the situation because she is "scared to death" of her actual captors.

"This is a sadistic situation, and she somehow was able to convince them to let her go," Mr Kelly told People magazine.

On the morning of November 22, Mrs Papini was found on the side of a highway nearly 240km away from her home. The mother-of-two was discovered by a passing motorist around 4.30am on Thanksgiving morning, allegedly chained, beaten and branded after vanishing three weeks prior.

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It is understood Mrs Papini, 34, was out for a jog 22 days earlier near her home in Redding, California, when she was kidnapped.

Earlier this month, Mrs Papini's husband Keith revealed intimate details of how his wife was found on the side of the road, including some of the injuries she sustained.

"She was bound ... she had a metal chain around her waist," Mr Papini told ABC News America's 20/20 program.

"She had a bag over her head ... she was chained anytime she was in a vehicle."

Earlier, Mr Papini described his wife's horrific injuries in minute detail, from the "bruises ranging from yellow to black because of repeated beatings" to the "severe burns, red rashes and chain markings" on her emaciated, 39kg body.

Following Mr Papini's interview, Shasta County Sheriff Tom Bosenko, who is leading the investigation into her alleged abduction, said Mrs Papini had provided the police department with valuable information relating to her abductors - who are still at large.

"Sherri described a sequence of events to the best of her recollection, remembering that she was held against her will and was isolated," he said during a press conference on December 1.

"Sherri described her assailants as two Hispanic female adults.

"She related that both of the subjects spoke in Spanish majority of the time during her captivity."

Mr Bosenko said the two described captors were armed with a handgun, and concealed their faces in an attempt to hide their identity from Mrs Papini.

"Suspect one was the younger of the two suspects," Mr Bosenko said.

"She had long curly hair and a thick accent. She had pierced ears and thin eyebrows.

"Suspect two was the older of the two suspects. She had straight black hair with some greying colour and had thick eyebrows."

But Mr Kelly, who is the founder and president of online serial killer profiling group S.T.A.L.K. Inc., said it was absolute luck and "an act of God" that her captors let Mrs Papini go.

"She somehow got them to believe she would not squeal on them," he said.

"It's only by an act of God they let her go. I have a hard time understanding that as a sadistic these [people] are - and I've hunted many of them - would let someone live."

Mr Kelly believes that Mrs Papini does have the knowledge and recollection to identify her captor, but says if they know where she lives then "she will always worry".

According to Mr Kelly, the branding could be a sign that Papini's abductors wanted her for sex-trafficking, but he said he wouldn't be surprised if the branding was done to "throw the case off."

"It's called staging," he said.

"They've set up that it was two women, and that they picked on you [Mrs Papini] because you are this all-American girl, that they are Hispanic and upset with the political climate, and we will tattoo a message on you that corresponds."

The investigation into her alleged abduction continues, who they still believe are two women of Hispanic appearance