FOWLER, N.Y. - A northern New York couple used a dog to lure two Amish sisters from their family farm stand in a plan to turn the girls into slaves, an investigator said Thursday.

Nicole Vaisey admitted she and her boyfriend, Stephen Howells Jr., got the girls to their car on Aug. 13 with an offer to pet the dog and he shoved the 7-year-old and 12-year-old sisters in, St. Lawrence County Sherriff's Sgt. Brooks Bigwarfe said.

Bigwarfe said she told him they shackled the girls.

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"She called it a shopping trip and they wanted to make the two girls their slaves," Bigwarfe said, according to CBS affiliate WWNY.

He said the couple, frightened by news reports of the abduction, released the girls about 24 hours later.

Fowler Justice Paul Lamson ruled Thursday there's reasonable cause to believe Vaisey committed felony kidnapping. He ordered her held without bail.

Howells, who also is jailed, waived his right to a hearing.

District Attorney Mary Rain said the children were sexually abused by the "sexual predators."

Bigwarfe said Vaisey told him the sisters were "handcuffed together at the ankles and handcuffed to the bedpost because they were scared they were going to go out the window and flee the house."

Bigwarfe testified that Vaisey, 25, and Howells, 39, became scared after hearing news reports on the girls' abduction "and they decided to drop the kids off in an isolated area." Vaisey went first, scouting the area to make sure there were no police around, and then Howells drove the girls to the site and dropped them off, the investigator said.

The girls walked until they found a home and knocked on the door, asking the residents for help.

Defense attorney Bradford Riendeau said Vaisey was under Howells' control.

"She was in a master-slave relationship," Riendeau said. "I believe she's not as culpable as he is."

The girls' kidnappings touched off a massive search in the Amish family's remote farming community. Searchers scoured the community of about 4,000 people but were hampered by a lack of photos of the girls.

The Amish typically avoid modern technology, and the family had to work with an artist who spoke their language, a German dialect known as Pennsylvania Dutch, to produce a sketch of the older girl.

The parents, who have 14 children, did not express anger toward the suspects.