An upstate New York couple accused of kidnapping two Amish girls planned on using them as slaves but let them go because they were scared of being caught, investigators told the Associated Press on Thursday.

Stephen Howells Jr. and Nicole Vaisey were arrested last week after kidnapping a 7-year-old girl and her 12-year-old sister from their family's vegetable stand on a farm in Oswegatchie, St. Lawrence County.  

The couple came across the sisters when they drove up to the farm's vegetable stand, where the girls would regularly tend to customers.

Vaisey, 25, told investigators she and her boyfriend lured the girls to their car by promising they could pet a dog before shoving them inside, St. Lawrence County Sheriff's Sergeant Brooks Bigwarfe told the AP.

Once they abducted the girls, the couple shackled them and intended to use them as slaves, Bigwarfe said. But they released the sisters about 24 hours later once news of the kidnapping spread.

The sisters were sexually abused during the time they were taken Aug. 13 and found the next day by a good Samaritan in Richville, District Attorney Mary Rain told the AP. Richville lies less than 20 miles from the girls' farm in Oswegatchie.

Bradford Riendeau, Vaisey's defense attorney, said her 39-year-old boyfriend dominated Vaisey and that she was his slave.

"She was in a master-slave relationship," the attorney told the AP. "I believe she's not as culpable as he is."

Vaisey was held without bail after a judge ruled Thursday there was enough evidence to charge her with felony kidnapping. Howells waived his right to a hearing and is currently jailed.

The sisters, the youngest of 14 siblings, live in one of the largest Amish communities in New York, according to the AP. Their parents said Thursday the girls appear to be fine and that the farm stand is operating again.