Miranda Barbour, 19, and her husband Elytte, 22, are accused of killing Troy LaFerrara, 42, who police say responded to a "companionship" ad she placed on Craigslist.
Police added Elytte Barbour strangled LaFerrara as he sat in the driver's seat of his car in the back yard of a Sunbury home while Miranda Barbour stabbed him at least 20 times.
In an interview from prison with the (Sunbury) Daily Item, Miranda Barbour said she had killed before, saying the number was "under 100," and that she stopped counting at 22.
Barbour told the newspaper the killings occurred during a six-year period in Alaska, Texas, North Carolina and California, and added she was part of a satanic cult.
Investigators in those states began reviewing cold-case files but experts who study serial killers have their doubts, CNN reported Tuesday.
"Anything is possible and, of course, it's conceivable she's a serial killer," Northeastern University criminologist Jack Levin said, while adding the caveat that few women are serial killers and those who are tend to be older than Barbour and do not use knives.
Authorities have not corroborated any of her claims.
Monica Caison, founder of a missing persons center in North Carolina, said, "[When] anything like this happens, we start getting e-mails and phone calls [about missing loved ones]. You can't just say you've killed 22 people between this region and that region ... . That's a lot of people to kill in such a short time."