May 28 (Bloomberg) -- As Brooke Astor approached her 100th birthday, and her memory and acuity flagged, her only son took on one of her favorite hobbies: estate planning, according to Astor’s longtime lawyer, Henry Christensen III.

Testifying in the trial of Anthony Marshall yesterday, Christensen said that after years of being excluded from the estate planning of his mother, one of New York’s top philanthropists, Marshall leaped to take a central role. Since the 1950s, Astor had written or revised her will more than 30 times, Christensen testified earlier.

“He called and said, my mother wanted to do ‘x,’” Christensen said yesterday in New York State Supreme Court, recounting a typical telephone call around 2000. “He started in some instances becoming the messenger.”

Prosecutors are relying on Christensen to buttress their claim that Marshall exploited his mother’s condition in the last years of her life, amending her will in his favor to steal from her. A lawyer he worked with, Francis Morrissey, is standing trial with Marshall. They are charged with conspiring to defraud Astor from 2001 to 2007, according to the indictment. Both pleaded not guilty.

Astor died in 2007, at 105. Her third husband was Vincent Astor, who died in 1959. He was heir to the fur and real-estate fortune amassed in the 19th century by John Jacob Astor, who in his time was the wealthiest man in the U.S.

Jargon-Filled Testimony

The jargon-filled testimony yesterday isn’t for the uninitiated. Several spectators who showed up in the morning were gone by lunch.

In the late afternoon, Christensen’s answers portrayed Marshall as increasingly calling the shots in his mother’s affairs before she died. Marshall turns 85 this weekend.

Known as “Terry,” Christensen worked at Sullivan & Cromwell LLP for 37 years before he joined McDermott Will & Emery in 2007, and had represented Marshall and Astor. Prosecutors presented a June 1999 letter to him in which Marshall suggested that his mother transfer the Upper East Side apartment where he lived as a bonus for his performance in managing her finances. The apartment had an assessed value of $2.1 million.

In the letter, Marshall said the $300,000 a year he was earning overseeing about $70 million of her mother’s money was about half what he deserved, based on the standard money manager fee of 1 percent of assets. Christensen, 64, said calling the transfer a bonus rather than a gift would have meant lower taxes overall for mother and son.

More Control

Christensen wrote a “first and final” codicil to Astor’s will in December 2003 that gave Marshall more control over her money when she dies. In January 2004, Christensen was fired and other lawyers drafted a second codicil that added millions to what Marshall stood to receive directly, prosecutors said.

Christensen testified that he learned in December 2000 from one of Astor’s doctors that she had second-stage Alzheimer’s disease, which impairs reasoning and language skills. A year later, the lawyer said Astor told him she wanted to sell a Childe Hassam painting she had previously prized.

“She said something about needing the money,” Christensen said.

Prosecutors charged that Marshall falsely informed his mother that she was running out of money -- even though she had assets worth more than $150 million. Marshall allegedly induced her to sell the painting, “Up the Avenue from 34th Street, May 1917,” according to the indictment. After arranging for a $10 million sale at a private gallery, Marshall earned a $2 million commission, according to the indictment.

“I told her she had more money than she could possibly spend,” Christensen said.

He’s scheduled to continue testifying today.

The case is People v. Marshall, 06044-2007, New York Supreme Court, New York County (Manhattan).

To contact the reporter on the story: Philip Boroff in New York at pboroff@bloomberg.net;

Last Updated: May 28, 2009 02:41 EDT