Denver ? A historic castle where John D. Rockefeller and Theodore Roosevelt were guests — and where a coal baron’s ghost is said to haunt the halls — was auctioned for $4 million Saturday, two years after the IRS seized the century-old mansion in a fraud investigation.

A Pasadena, Calif., man made the winning bid, said John Harrison, an IRS special agent. The unidentified buyer declined to talk with reporters.

IRS agents seized the 42-room Redstone Castle in the mountains near Aspen in March 2003 while investigating an international Ponzi investment scheme. They also seized about $17 million in cash from bank accounts and race cars worth $2 million.

The castle’s previous owner, Leon Harte, was being investigated before he died in 2003. Court documents said Harte and others had formed three companies to buy the castle and the Victorian home for $6 million five years ago.

Investigators say about 1,000 people were bilked of a total of $56 million on the promise of 400 percent investment returns. A grand jury indicted seven people last year and trial proceedings are scheduled for September.

Proceeds from the auction will help reimburse victims, Harrison said.

The sale was the latest twist in the castle’s almost epic past. Teddy Roosevelt stayed at the estate during a hunting trip after he left the White House; oil tycoon John D. Rockefeller did, too.

But it was nearly abandoned after a mining bust, and some say the ghost of its builder, coal baron John Cleveland Osgood — who died in the castle he named Cleveholm Manor — still haunts the place.

The castle, surrounded by a carriage house and other outbuildings in the Crystal River Valley about 170 miles west of Denver, was finished in 1902 at a price of $2.5 million — an astonishing sum at the time.