A North Andover man Wednesday pleaded guilty to charges that he physically and sexually abused two stepdaughters for years, sometimes by demeaning their ethnic heritage, forcing them to use the Nazi salute, and twisting their tongues with pliers, Essex prosecutors said.

His wife, and the mother of the two girls who are now 15 and 17 years old, also pleaded guilty in Essex Superior Court to allowing some of the acts of abuse to take place in her presence, according to Essex District Attorney Jonathan Blodgett’s office.

“While there is no amount of jail time that would reflect the utter depravity of the defendants’ conduct, this agreement spares the victims the additional trauma of a trial,’’ Blodgett said in a statement.

He called the two sisters “true survivors’’ and held out the hope that learning of the guilty pleas “helps them to understand that what happened to them was not their fault.’’

The stepfather was identified as Justin Ladd, 35, who pleaded guilty to 32 counts of assault and battery with a dangerous weapon, indecent assault and battery, open and gross lewdness, and assaulting a person because of their race, prosecutors said.

According to prosecutors, over a five-year period he repeatedly abused the two girls, whose father is ethnically Dominican, telling them they “aren’t white, they aren’t right,’’ ordering them to dance like monkeys, and hitting them with a hammer, belt, and pieces of wood.

He also admitted to exposing himself to them and threatening to have members of the Hells Angels motorcycle gang rape and murder them if they disclosed the pain he was inflicting on them. Ladd, who has “white power’’ tattoos, had a Nazi swastika on the walls in his home and ordered the girls to give him the Nazi salute, prosecutors said.

He was sentenced to four to five years in state prison and five years probation after his release, when, among other requirements, he is to attend a parenting class. He will also be required to wear a GPS monitoring bracelet once released from prison.

His wife, identified by prosecutors as 34-year-old Anne Ladd, pleaded guilty to two counts of reckless endangerment of a child and two counts of permitting bodily injury to a child, prosecutors said.

She was sentenced to five years probation, a term recommended by both prosecutors and the defense, and may only see her children while under the supervision of the Department of Children and Families — if her daughters want to see her, prosecutors said.

The teens have been placed in foster care, prosecutors said.

John R. Ellement can be reached at ellement@ globe.com. Follow him on Twitter @JREbosglobe.