SAN FRANCISCO (AP) — Attorneys representing kidnapping survivor Jaycee Dugard are demanding a judge sanction U.S. Department of Justice lawyers for alleged witness tampering.

In court papers filed Monday, Dugard's attorneys allege that DOJ lawyers unfairly convinced the former chair of the U.S. Parole Commission to cease serving as Dugard's expert witness in her lawsuit against the federal government.

Dugard alleges U.S. parole officials are partly to blame for her abduction and 18 years of captivity at the hands of a convicted rapist Phillip Garrido, who was on parole after serving 11 years of a 50-year sentence.

Dugard's lawyers are seeking a verdict in their favor because of the DOJ's actions. She and her two children have already received a $20 million settlement from state of California.

Justice Department officials did not return phone calls and emails seeking comment late Tuesday.

Garrido and his wife abducted Jaycee from a street in South Lake Tahoe in June 1991 while on her way to school. She was 11 years-old. The couple kept Dugard captive in a backyard compound behind their Antioch house where Garrido repeatedly raped and drugged the girl. During her captivity, Dugard gave birth to two daughters fathered by Garrido.

Dugard alleges in her federal lawsuit that federal parole agents failed to meet with Garrido as frequently as required and that agents failed to properly report his frequent marijuana use. The lawsuit also alleges that federal parole officials failed to turn over Garrido's file when his supervision was transferred to California parole officials.

In short, the lawsuit alleges that federal parole officials should have revoked Garrido's parole prior to his kidnapping of Dugard.

Garrido was sentenced to 431 years to life for kidnap and rape. His wife Nancy was sentenced to 36 years to life.

In the court filing Monday, Dugard's lawyers complain that the Department of Justice has fouled up their case by contacting their sole expert witness. They say they spent more than 50 hours over three months working with Carol Getty, who was prepared to testify on Dugard's behalf. Getty served as chair of the U.S. Parole Commission from 1991 to 1992.

Dugard's attorney Dale Kinsella alleges that Department of Justice lawyers called Getty on Aug. 1 and told her that it was improper to serve as an expert witness because she was actually involved in the lawsuit since she served on the commission during the some of the time in question. On that day, Getty told Dugard's lawyers she wanted nothing to do with them anymore and hung up the phone in mid-sentence.

Kinsella says it "comes as no surprise that her name appears on a commission document during that time period" but that there is no evidence that she was directly involved in Garrido's case. In fact, one of the main claims of the lawsuit is that agents failed to report Garrido's marijuana use to the commission so it could decide whether to revocate his parole.

Kinsella argues that the government's action is part of a broader strategy to prevent Dugard from hiring an expert witness to bolster her case. Kinsella says that DOJ has told him it intends to seek a judicial order barring Dugard's legal team from hiring any former government workers to serve as expert witnesses. Kinsella said such an order would be "dire" for Dugard's case because there are no other experts available.

A hearing has been scheduled for Sept. 10.