NEW YORK (AP) – Greed and his preoccupation with amassing money for his third wife led the son of the late socialite Brooke Astor to loot his aging and ailing mother’s $198 million estate, a prosecutor told jurors Monday.

Anthony Marshall exploited his mother’s diminished mind to steal cash and property worth millions of dollars, Assistant District Attorney Elizabeth Loewy said.

She said he later got help from lawyer Francis X. Morrissey, his codefendant.

“This case is about greed, the greed of two men, Anthony Marshall and Francis Morrissey, to increase their own wealth at her expense,” Loewy told jurors in opening statements at the trial in Manhattan’s state Supreme Court.

Loewy said Astor was diagnosed with Alzheimer’s disease in 2001, but the defendants still had her sign papers and make will changes that bewildered her. Astor died in August 2007 at age 105.

The will changes increased Marshall’s share of his mother’s estate, Loewy said. She said one change left him $60 million Astor had intended for charities.

Loewy said Marshall, 84, told his mother falsely that she was going broke and he had to sell some of her paintings to raise money. She said he sold one artwork for $10 million and kept a $2 million commission for himself.

As Astor’s financial adviser, Marshall was paid $500,000 a year. In 2005, Loewy said, he gave himself a raise to $1.4 million and made the salary hike retroactive to cover all of 2004.

The prosecutor said Marshall also bought himself a 55-foot yacht for $900,000 and used his mother’s money to pay the boat captain’s $52,000 yearly salary.

Loewy said Marshall’s wife, Charlene, exerted a strong influence on him.

“His actions became more aggressive and more brazen with Charlene behind the scenes pressuring to get more from his mother,” the prosecutor said.

In one case he transferred Astor’s Maine home to himself and later “quietly” transferred it to his wife, Loewy said. A Manhattan judge made her return it to the estate two years ago.

Loewy said Charlene Marshall knew that under Astor’s original will in 2002, she would have gotten virtually nothing if Marshall had died. Loewy said Astor “simply didn’t like Charlene.”

The case was prompted by a court petition filed by Philip Marshall, a Massachusetts college professor and Astor’s grandson. His court papers said his father was robbing Astor and neglecting her health and hygiene.

Loewy said Anthony Marshall “was making sure his mother didn’t spend his inheritance, money that he already considered to be his own.”

Philip Marshall’s complaints prompted the investigation that led to his father’s indictment and removal as Astor’s guardian.

Anthony Marshall, a former diplomat and Broadway producer, is charged with grand larceny, possession of stolen property, scheme to defraud and other charges. If convicted of grand larceny he could be sentenced to 25 years in prison.

Morrissey, 66, hired by Marshall, was indicted on forgery charges and scheme to defraud. He faces up to seven years if convicted.

The defense will present opening statements Tuesday, but Marshall’s lawyer, Kenneth Warner, has said the socialite changed her will because she loved her son and wanted to make him happy.