Arrests made in thefts of Yogi Berra World Series rings, Roger Maris MVP trophy - ESPN

Federal authorities announced charges against a ring of nine people for thefts of millions of dollars worth of paintings, sports memorabilia and other valuables including World Series rings belonging to baseball legend Yogi Berra and an MVP trophy awarded to New York Yankees teammate Roger Maris.

The thefts took place over more than two decades at 20 different museums and institutions across Pennsylvania, New Jersey, New York and North Dakota, the U.S. Attorney for the Middle District of Pennsylvania said Thursday.

Investigators believe some of the sports memorabilia had been melted down, including nine of Berra's 10 World Series rings, U.S. Attorney Gerard M. Karam said at a news conference.

The theft ring also allegedly stole an Andy Warhol silkscreen, a Jackson Pollock painting and the Hickok Belt awarded to Maris in 1961, when he set Major League Baseball's single-season record with 61 home runs. The Hickok Belt was given to the top athlete in the United States from 1950 to 1976.

It was unclear which items would be returned to their owners or to the museums, but authorities said some of those valuables had been recovered.

Eight of the nine people named as part of the theft ring have turned themselves in, Karam said. At least five had already entered into preliminary plea agreements on charges including theft of major artwork and conspiracy to dispose of major objects of cultural heritage, according to court records. The suspects are in their late 40s to early 50s and are Pennsylvania residents.

Karam said the ninth suspect, 53-year-old Nicholas Dombek, is considered a fugitive.

The indictments allege the thieves transported the memorabilia and valuables and would melt the gold items down into transportable discs that