Miranda Barbour, 19, also said she had killed at least 22 people in different parts of the country, Sunbury, Pennsylvania's Daily Item newspaper said, and that she was involved with a Satanic cult.
"When I hit 22, I stopped counting," she said on the paper's website. She now just wanted to be honest, she said.
She and her husband, Elytte Barbour, 22, in separate appearances at a state court in Sunbury in December pleaded not guilty to the November 11 killing of 42-year-old Troy LaFerrara, whose body was found dumped in an alley in Sunbury.
A public defender who represented Miranda Barbour at the arraignment could not be reached for comment on Saturday, nor could an attorney for her husband.
The Daily Item, which has a circulation of about 25,000, has been following the case closely, reporting on the Barbours' arrest, a police search of their home and court hearings for the two defendants.
Prosecutors say the husband hid under a blanket in the back of their car when his wife picked up LaFerrara at a mall near Harrisburg, about 50 miles south of Sunbury.
On her signal, Elytte Barbour strangled LaFerrara with a cord while his wife stabbed him about 20 times, police say.
"He said the wrong things and then things got out of control," she said. "I can tell you he was not supposed to be stabbed. My husband was just supposed to strangle him."
A Sunbury police investigator on the case could not be reached for comment late on Saturday.
It was not clear if police have any evidence that might link Miranda Barbour to killings other than LaFerrara's.
Sunbury Police Corporal Brad Hare in December told Reuters the Barbours "just wanted to murder someone together".
(Reporting by Alex Dobuzinskis; Editing by Louise Ireland)