Here is some additional info gleaned from the internet:
The best known case of looting by American personnel was the theft of the Hesse Crown Jewels. The primary instigator of the theft was Captain Kathleen Nash. Nash, Major David Watson and Colonel Jack Durant, Nash’s lover, found a fresh patch of concrete in the cellar as they were exploring the castle. They chipped through the concrete and found zinc lined boxes full of jewels. The trio removed the jewels from the tiaras, bracelets, etc and sold them in Switzerland. In late 1945, the trio returned to the United States. In addition to the jewels and gold, the trio had looted silverware, books, and hundreds of other items. In January 1946, the jewels were reported missing by a member of the Hesse family. The Army’s Criminal Intelligence Division determined the extent of the theft and soon arrested the trio. Durant married Nash so she would not be allowed to testify against him. Watson was sentenced to three years in prison but was released after four months. His family owned a large West Coast grocery store chain that apparently had connections to people in power. Durant was sentenced to fifteen years and released after six years. Nash however, was described as a difficult prisoner and served her entire sentence of five years. About one half of the jewels had been mailed to Nash’s sister.
The Hesse Crown jewels were discovered by an American soldier and a civilian in November 1945 in a castle used by Allied soldiers. The two turned the jewels over to the soldier's company commander, Capt. Kathleen Nash, after which the jewels disappeared. After an extensive investigation, Capt. Nash and another officer were convicted of smuggling the valuables out of the American Occupational Zone. In 1951, the collection of 270 diamonds and other jewels was returned to the Hesse family.
The Americans prosecuted a theft in the millions by a U.S. welfare officer, Captain Kathleen Nash and Colonel James Durant, from the castle that the Army was using as a recreation club. The army had requisitioned the Hesse family home and castle, driving the family elsewhere. The jewels were discovered although they had been well hidden, in a welded-shut metal box behind brick and mortar, and the officers thought that the Hesse family were just a bunch of Nazis anyway and why not take their share of victor's loot. 60
60. A video tape on this (Secret Plunder -- GI Loooters) is available at The History Channel.
As a result of the increased attention given to its public image after World War II, the Corps suffered few ignominious incidents like the one that occurred in 1946-the court-martial of Capt. Kathleen Nash Durant, her husband, and several others in Germany for the theft of the royal jewels of the House of Hesse from Kronberg Castle in Frankfurt. Most of the jewels, valued at over a million dollars, were recovered, and Durant was found guilty of larceny, dishonorably discharged, and sentenced to serve five years at hard labor at the Federal Reformatory for Women in Alderson, West Virginia. She was paroled on good behavior in 1949
10 History of the Second Year of the Occupation Forces in Europe, 1 Jul 46-30 Jun 47, Office, Chief of History, European Command, p. 26, CMH Ref Br; New York Times, 29 Jul 49, p. 1.
One website had a picture with the following caption:
In February 1947, the 709th MP Battalion provided an escort detail to accompany the evidence that was collected in Germany during the investigation of the theft of the Hesse Crown jewels. The evidence was transferred to the US for the trial. The photo to the left appears to show members of the 709th MP Battalion carrying a crate of evidence relating to the Hesse Crown Jewels Robbery from an Air Transport Command aircraft at Bolling Field, Washington DC. (Acme News Photograph, February 3, 1947.)