CANTON, N.Y. >> More charges are expected soon against a northern New York couple accused of kidnapping two young Amish sisters and sexually abusing them, a prosecutor said Sunday.

Computer hard drives and other potential evidence are still being collected Sunday from the home of Stephen Howells Jr. and Nicole Vaisey, said Mary Rain, district attorney for St. Lawrence County.

The pair was arrested Friday and charged with kidnapping with the intent to physically or sexually abuse the 7-year-old and 12-year-old sisters. Authorities say the couple prowled for easy targets and sexually abused the girls before letting them go after about 24 hours.

Howells, 39, and Vaisey, 25, are being held without bail and have a preliminary court appearance scheduled for Thursday.

“I 100 percent expect more charges,” Rain told The Associated Press in a telephone interview. She said the new charges, which she would not detail, could come after she meets with police investigators Monday or at the hearing Thursday. It’s also possible prosecutors would have to wait for results from forensic tests.

The sisters were abducted Wednesday from a farm stand in front of the family’s home in Oswegatchie, near the Canadian border. They were set free by their captors about 24 hours later and turned up safe at the door of a house 15 miles from where they were taken.

There was no answer Sunday at the St. Lawrence County Conflict Defender’s Office, which is representing Howells.

Vaisey’s lawyer, Bradford Riendeau told The New York Times that she was in an abusive and submissive relationship with Howells. He said she made a “voluntary statement” to investigators after her arrest and was obtaining an order of protection against him.

“She appears to have been the slave and he was the master,” Riendeau told the newspaper.

Rain said Vaisey is just as culpable as Howells.

St. Lawrence County Sheriff Kevin Wells said the girls were able to provide details to investigators about their time in captivity.

The Associated Press generally does not identify victims of sexual abuse and is not naming the girls.

The kidnappings touched off a massive search in the 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.