She was reported missing the same day as Sherri Papini. What happened to Stacey Smart?

While women across Australia and America have been transfixed on the mysterious kidnapping of American woman Sherri Papini, another woman reported missing the same day remains unfound.

Mrs Papini, 34, was reported missing after she failed to return from a run on November 2 in California.

Twenty-two days later, the mother of two was spotted by motorists on the side of a rural road at 4.30am trying to flag down cars after being dumped there.

In a mysterious twist, a woman who disappeared on the same day, in the same area, is still missing.

Californian woman Stacey Smart was also reported missing on 2 November, but unlike Mrs Papani, she was not found on the side of a highway three weeks later.

The two women live about 40 kilometres from each other, north of Redding, but the Trinity County Sheriff’s Office said there does not appear to be a link between the two cases.

The 52-year-old's eldest daughter Nichole Santos-Hamann reported Ms Smart missing in November, but said she hadn't spoken to her mother since 12 October.

According to The Trinity Journal, Ms Santos-Hamann became concerned for her mother's welfare after not hearing from her over Halloween. Friends she contacted said they hadn't seen Ms Smart for several weeks.

The last activity on the Lewiston local's debit card was October 16.

Although Ms Smart's case has not captured the media's attention the same way Sherri Papini's alleged abduction has, her family and friends have launched their own campaign to "bring Stacey home" and conducted searches, along with the community, around the Lewiston area.

In an effort to raise enough money for a reward for information and a private detective, a GoFundMe fundraising page has been set up.

Ms Smart's family have spoken to self-described kidnap consultant Cameron Gamble, who was the man behind the video posted a day before Mrs Papini's return, which police now say they don't believe led to her release.

Ms Santos-Hamann said Mr Gamble spoke to the family about coming up with a bounty or reward for her mother.

“He’s helping us, he’s giving us advice and kind of helping us with coming up with backers, to help us with a bounty or reward leading up to her whereabouts, what could have happened,” she told local newspaper The Record Searchlight.

Ms Santos-Hamann said her mother does not have a history of mental illness and regularly checked in with family and friends.

Ms Smart's boyfriend Tony Brand told the Trinity Journal he believed she had left him without letting him know when she went missing mid-October.

“This whole time we’ve just been waiting for her to come back and show up and she hasn’t,” Mr Brand told the newspaper.

“I just hope and pray that she’s OK. I do really love the girl and we did have a lot of good times.”

Mr Brand has reportedly co-operated fully with investigators and allowed searches of his home and property.

Sightings of Ms Smart have been disregarded by Ms Santos-Hamann, who said witnesses may have confused her for her sister, Melissa Martin.

“I think they’re either off with their dates or they are thinking of my aunt, people get them mixed up all the time,” Ms Santos-Hamann said.

The investigation is ongoing.