NEW YORK – Manhattan prosecutors have launched a criminal probe into whether millions of dollars may have been fraudulently skimmed from Brooke Astor’s estate when she was 101 years old.

The investigation was sparked by a document examiner’s conclusion this week that Astor’s signature was forged on a March 2004 amendment to her will. That document will be among many that will be examined by prosecutors.

“In view of a finding that there’s been a forgery, we would take a look at the whole picture, not just a few documents,” a law enforcement source told the New York Daily News.

Lawyers also have questioned how Astor suddenly decided to give her son Anthony Marshall $5 million in cash and her beloved Maine estate in 2003.

In the following months, Astor changed her will three times to give the bulk of her estate to her son, to let him choose the charities that got donations from her fortune and to have her real estate sold after her death so the sales costs would be tax-deductible.

Two of those changes were signed in Astor’s shaky script, but the third signature is much bolder. A document examiner concluded Wednesday that Astor “could not have written” it “due to the deterioration of her ability to write her name.”

Astor’s court-appointed attorney, Susan Robbins, told The News she turned the report over to prosecutors and is prepared to provide any other documents.

“Forgery is a crime,” Robbins said. “But I don’t know who forged it, so I don’t know who committed the crime.”

The transactions were overseen by top estate lawyers Henry Christensen of Sullivan & Cromwell and Warren Whitaker of Day, Berry & Howard – as well as Francis Morrissey, a once-suspended lawyer who took an increasing role in Astor’s affairs in recent years.

None of them returned calls for comment Friday.

“We’re surprised at the allegation, obviously,” said Marshall’s lawyer, Ken Warner, who noted that his client wasn’t there when the amendment was signed.

Marshall’s son, Philip Marshall, who filed the original case, said he was shocked to learn that criminal prosecutors are getting involved.

“This news of a possible investigation realizes my worst nightmare that crimes against my grandmother may have been committed,” he said.

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