Oct. 8, 2009 -- Called the Battle of the Blue Bloods, it's a fight to the finish over the fortune of the late millionaire socialite and philanthropist Brooke Astor.
In one corner is her only son, Anthony Marshall, who was convicted of fraud, conspiracy and grand larceny for looting his mother's approximately $180 million fortune as she lay stricken with Alzheimer's disease. Marshall can face up to 25 years in prison. His wife, Charlene, was cast as the villain in her husband's five-month trial.
And who was the star witness against him? Philip Marshall, his son from his first marriage.
The case was set in motion when Philip filed to take over guardianship of his grandmother in 2006. Prosecutors called 72 witnesses to the stand in Anthony's five-month headline-making trial.
"There are people who probably would say, 'Well, how did I do this to my father?'" Philip said in an exclusive interview to air "20/20" Friday. "Quite frankly, what I did was help my grandmother, and he brought this upon himself. ... I don't think that there was anything innocent about what was being done to my grandmother."
"20/20" spoke exclusively to Philip, Tony Marshall and his wife, Charlene, in the weeks before the jury reached a verdict. Tony is now 85. Philip is 56. Brooke Astor died in 2007 at the age of 105.
According to Philip, who became close to his grandmother in later years, Astor was being neglected and his father was at fault. Marshall denied the allegations, calling them "malicious and false."
When Philip filed for guardianship of his grandmother, it set the groundwork for a criminal case against his father on counts of larceny and scheming to defraud. But why did he go to court and not to his father?
"On a good day it would have been great if I could simply talk to my father about this," Philip said. "But that was not the way our relationship was."
"I ended up calling my father and saying that guardianship had been filed. ... Charlene stayed on the line. And I said that I was sorry that I had to, had to do this. And she goes, 'Well, I bet you are.' Something to that effect. At which point I said, 'Well, I'm sorry you made me have to do this.'"
Philip said there were several events that prompted him to take action to protect his grandmother from his own father. He said Tony transferred the title of Astor's beloved Cove End estate in Maine to Charlene; sold a painting she had often said she wanted to go to the Metropolitan Museum of Art and kept a $2 million commission; and he closed her Westchester Country home without her ever knowing.
"She would not have wanted Maine to go to Charlene. I don't want to be presumptuous, but I think that's a fair understanding of the situation," Philip said.
Philip told "20/20" that it was never his intention to make the family disagreement public.
"When we filed we said, this will be settled quietly," he said. "I remember saying to my lawyer, 'Hopefully, you know, this news will be sealed, not will end up on Page Six.' And he said, 'No. It will end up on page one.' And he was right."
Brooke Astor's Family Speaks to '20/20'
A lifetime of family tension played out in tabloid headlines, exposing the complicated relationship between Brooke Astor, her son Anthony Marshall and his wife Charlene.
Perpetually in his mother's shadow, it seemed Anthony Marshall could do no right in her eyes -- especially when it came to Charlene, his third wife. Their courtship and 1992 marriage was marked by scandal in Northeast Harbor, Maine, where Astor had a waterfront estate and Charlene Gilbert -- then the local minister's wife -- fell for Marshall, who was also married at the time.
"I met Tony and fell in love with him, and I thought I was the luckiest girl in the world," Charlene told ABC News' Deborah Roberts in an exclusive interview. "When Tony first told his mother that he was getting divorced, she was thrilled. And she said, 'Oh, this is wonderful, you can escort me to all the dinners and parties.'
"Well, not long after that he told her that he was getting divorced because he wanted to marry me. Then she wasn't so thrilled."
"My grandmother really did not like Charlene," Philip told ABC News. "That was clear."
Philip, who says tensions with his father grew after the marriage to Charlene, told "20/20" that he was suspicious of his stepmother's intentions from the beginning.
"You have to wonder, was there some grand plan," Philip said, "Or was it simply love at first sight? And I think it might be mixed."
When asked by Deborah Roberts if he considered Charlene to be a gold-digger, Philip said the term "emerald digger" might be more appropriate. He suggested that Charlene may have had her eye on his grandmother's famous emerald necklace -- a gift from the late Vincent Astor.
"I think ... Charlene came from a family that, or as her family was, had very little money. And she saw an opportunity," he said.
While Brooke Astor acknowledged that Charlene made her son happy, many close to Astor said she never fully accepted her daughter-in-law -- ultimately snubbing Charlene in her will.
Philip Marshall: 'Charlene is Driving This'
In the very public criminal trial, the prosecution depicted Charlene as a greedy villain, and claimed it was Marshall's motivation to secure funds for his wife at a time when Astor was incompetent to make financial or legal decisions.
"I really believe as though Charlene is driving this," Philip said. "The plan seemed to have been that Charlene wanted as much as she could possibly get. Even a few million was not enough. That she wanted everything."
The prosecution claimed that Marshall had taken some of Astor's valuable artwork, among other things, and tricked her into changing her will, steering millions to Charlene and to him instead of to charity. The defense argued that Astor changed her will after warming up to her daughter-in-law.
"Over time we grew closer," Charlene told "20/20." "She realized that Tony and I truly were deeply in love. ... She would always just thank me profusely for being there and for taking such good care of him and for making him happy."
Philip disagreed, saying that it's not possible that Astor had a change of heart. "I think she probably didn't want much to go to Charlene," he said.
Tony Marshall insists he is innocent of the charges. On legal advice, Charlene and Marshall declined to discuss details involving the case.
'I'm Very Likely Disinherited'
Philip told "20/20" that filing for guardianship of his grandmother was never about the money.
"If I had wanted many, many millions, I probably would have done nothing, and figured that my father was going to leave, leave me a lot of money. At this point, I'm very likely disinherited, and that's the many, many millions that are likely gone. I was glad to do that, for the cause," he said.
Though the trial has made a public spectacle of the Astor name, Philip said it has also brought national attention to the issue of elder abuse.
"She didn't choose this. ... Certainly she wouldn't like what's happening, but look what it's doing, in terms of addressing an incredible cause," he said. "And I think what the result of what we're in the fray of now, and how this will extend beyond Brooke, is really personally very important, about how this will inform the greater discussion of elder justice."