FOWLER, N.Y. — A northern New York couple used a dog to lure two Amish sisters from their family farm stand with a plan to turn them into slaves, an investigator testified on Thursday at a hearing.

One suspect, Nicole F. Vaisey, admitted that she and her boyfriend, Stephen M. Howells II, got the 7- and 12-year-old girls to their car with an offer to pet the dog and that he shoved them in, Sgt. Brooks Bigwarfe of the St. Lawrence County sheriff’s office said.

Sergeant Bigwarfe said that Ms. Vaisey told him they shackled the girls and intended to turn them into slaves. He said they released the girls about 24 hours later, frightened by news reports.

Justice Paul Lamson ruled on Thursday at the town court here that there was reasonable cause to believe Ms. Vaisey committed felony kidnapping. He ordered her held without bail.