Author and former Montana resident Brian D’Ambrosio was sentenced Monday to six months in federal prison and ordered to pay $22,508 in restitution for stealing materials from the Montana Historical Society, the U.S. Attorney’s Office announced in a news release.

D’Ambrosio, 50, will be allowed to self-report to a federal prison in Texas within the next few weeks, according to a news release. He also was fined $4,000.

“D’Ambrosio’s actions were intentional and calculated — designed to steal Montana’s cultural treasures so he could profit,” said U.S. Attorney Jesse Laslovich in a statement. “The Montana Historical Society, and all Montanans, were victims of D’Ambrosio’s greed because these documents were deeply rooted in Montana history. Today, D’Ambrosio faced the consequences, and we hope this case serves as a deterrent to anyone considering similar criminal conduct.”

D’Ambrosio requested a sentence of five years’ probation, but U.S. District Court Judge Brian Morris said jail time was warranted to reflect the seriousness of stealing irreplaceable documents from historical institutions and to provide deterrence, according to a news release from the Montana Historical Society.

The judge said that D’Ambrosio’s excuse that he stole the items during a difficult time in his life didn’t explain his actions.

“I appreciate the personal struggles in your life, but in my experience, trauma in a life doesn’t equate … (to doing this) over and over again at a historical society,” Morris said, according to the organization. “When someone does something stupid, it’s usually a one-time thing. But this happened over and over again; how does tragedy in your life translate to your actions at the historical society?”

D’Ambrosio’s response was inaudible to the 20 members of the Montana Historical Society in the courtroom,  according to the organization.

D’Ambrosio’s attorney, Colin Stephens, wrote in a sentencing memo that everyone involved in the case was struggling to reconcile the actions taken by his client, according to the news release from the historical society.

“The circumstances of the offense are those of a man in deep personal pain, who seemingly lashed out at one of the few places that used to provide him comfort,” Stephens wrote. “Now, because in the moment he could not find a healthy way to deal with his pain, Brian has lost his reputation, and he is barred access from the tranquility of the Historical Society, and the quiet peace it gave Brian, surrounded by the sense of the permanence of history.”

The government in court documents said that D’Ambrosio’s actions targeted artifacts that would reap large profits, and he stole items from the archives from about April 2022 to September 2023.

The stolen items included letters written by Nancy Russell, the wife of renowned Western artist Charlie “C.M.” Russell. They were more than 100 years old, were of cultural heritage and exceeded $5,000 in value. D’Ambrosio sold and attempted to sell the stolen items for profit on eBay.

An undercover FBI agent posed as a would-be purchaser to confirm D’Ambrosio was the individual stealing the items from the Montana Historical Society and selling or attempting to sell the items.

D’Ambrosio said during that time, his mother died, and both a daughter and his father faced medical difficulties.

In a statement from the Montana Historical Society, Tim Fox, president of the Board of Trustees, said he was satisfied with the prison sentence.

“Every item in our archives is a treasure of immeasurable value to our great state and its people,” said Fox, also former Attorney General. “D’Ambrosio’s egregious and outrageous crimes violate all sense of decency and trust. A hallmark of our society is that libraries, museums, and archives are open and accessible to the public. The defendant violated that trust, committing these crimes for personal gain, profit and prestige.”

D’Ambrosio initially was indicted by a grand jury in 2023 on 10 felony charges, including theft of major artwork, interstate transportation of stolen property, and seven counts of wire fraud, according to the Montana Historical Society. Under a plea agreement, he admitted to the theft of major artwork, and the other nine counts were dropped, the Montana Historical Society said.

Some of the items were returned, but Montana Historical Society Director Molly Kruckenberg said the damage from the theft will be ongoing – not just trying to recover the remaining stolen items, but also to restore staff’s trust and lessen the impact on future researchers.

“This damage goes beyond the walls of the Montana Historical Society’s Library and Archives; museums around the country are asking themselves – again – how to balance access and trust when a trusted researcher becomes a common thief,” Kruckenberg said. “Rest assured, we are working diligently to restore the trust Brian D’Ambrosio selfishly took from us. But we will never forget what he did.”

The Montana Historical Society staff also said because of the thefts, the organization changed its policies.

“The items stolen by you (D’Ambrosio) from the collections belong to the people of Montana, not to you for your selfish, greedy purposes. Your actions forced us to implement stricter rules regarding access and use of historical documents, which impacts all future researchers. … The emotional and financial impacts will be felt for generations.”

The U.S. Attorney’s Office prosecuted the case. The FBI Art Crime Team and Helena Police Department conducted the investigation.