LAS VEGAS (AP) - A defense lawyer on Wednesday challenged prosecutors to prove 45 felony child abuse or neglect charges filed against his clients, the owners of a shuttered private boarding school for at-risk teens in rural Nevada.

“Good luck trying to prove your case,” said Thomas Gibson, attorney for Marcel Chappuis and Patricia Chappuis, a married couple accused of subjecting students at Northwest Academy to physical, mental and verbal abuse and forcing them to drink tainted tap water.

Nye County District Attorney Chris Arabia alleged in court filings the students were subjected to “unjustifiable physical pain or mental suffering” and the school owners failed to properly screen and supervise staffers.

“These children suffered and that’s simply unacceptable,” Arabia said.

A conviction could get Marcel Chappuis, 73, and Patricia Chappuis, 67, decades in state prison.

Gibson said Wednesday his clients plan to waive arraignment Aug. 19 in a local court in Beatty and fight the charges at a preliminary hearing at a date to be set.

Marcel and Patricia Chappuis remain free on bail set following their arrests Feb. 14.

The Las Vegas Review-Journal reported the charges correspond with the number of students enrolled between February 2018 and February 2019 at the school in Amargosa Valley.

An investigation of the school some 90 miles (145 kilometers) west of Las Vegas began in January, after a staff member was arrested on suspicion of slamming students to the ground. He was not charged with a crime.

The Review-Journal found several state agencies failed for more than two years to address problems including dozens of Nevada Division of Environmental Protection violations written after tap water treatment stopped in October 2016.

Students, parents and school staffers describe students being dragged by their necks, handcuffed to chairs and subjected to inappropriate sexual behavior with staff members.

However, the newspaper said the state Department of Health and Human Services, which licensed the school as a child care facility, found many of the claims unsubstantiated.