Ida Gatti, a 67-year-old mother of six, told a court Tuesday that wills were a private matter and not something she discussed with the former welterweight champion.
The Gatti clan -- represented by his mother and youngest brother -- is in a legal battle with the ex-boxer's widow, Amanda Rodrigues.
The Gattis claim Arturo was pressured, weeks before his death in 2009, into signing a will that left everything to Rodrigues. They want it declared invalid.
They say Gatti had a second, earlier will -- which has gone missing -- leaving his fortune to the family.
Ida Gatti told the court Tuesday the only time that she'd heard of a will that listed her and her youngest son Fabrizio as benefactors was at his funeral in Montreal.
Testifying in her native Italian, Ida Gatti said through a translator that she never questioned her son about a will.
"No, because a will is private," she said when cross-examined by Pierre-Hugues Fortin, Rodrigues' lawyer.
A civil trial aimed at deciding who will get her late son's fortune is into its second week in Montreal and has been beset by events abroad.
Those include the release a private probe into Gatti's death; a wrongful death suit filed in New Jersey by the mother of Gatti's first child and reports that Brazilian authorities are again looking into Gatti's death.
On Tuesday, a lawyer in New Jersey told The Associated Press that he filed the wrongful-death on Sept. 9 in Middlesex County against Rodrigues.
The suit was filed on behalf of five-year-old Sofia Bella Gatti. It seeks damages and restraints on the couple's New Jersey assets.
Gatti's friends have testified that the couple was spilt up and heading for divorce. Despite this, they travelled frequently leading up to his death in 2009 -- including trips to Europe and the Caribbean.
Ida Gatti testified that relations between Rodrigues and her son had deteriorated by early 2009. She said she was witness to some of the fights between the couple.
However, Gatti admitted under cross-examination she can't read English or French. She said she only understands some English -- mainly curse words. English would have been the language spoken between the couple.
"My son (later) explained to me things in Italian," she said.
Ida Gatti said the relationship wasn't always so bad.
The court saw happy-looking family photos from a Christmas gathering in 2007 and a trip to Cuba in 2008.
She was also present in the room when Rodrigues' gave birth to Gatti's second child -- Arturo Jr.
Although she said she found her future daughter-in-law bizarre at the beginning, she later grew fond of Rodrigues and found her charming. She says the young woman even eventually called her "Ma."
She said Rodrigues once told her she loved Gatti and said Arturo was her life. But as the relationship went on, she said, the arguments between the pair became more frequent.
Ida Gatti said the last time she saw her son was just before he left for Brazil, a trip she couldn't comprehend because she believed they were headed for divorce.
She says she warned him not to go -- that Rodrigues didn't love him and that it was a trap. Days later, Gatti was found dead in a hotel room in a Brazilian seaside resort.
Police ruled his death a suicide but a private report, funded by Gatti's ex-manager, says the boxer's death was clearly a homicide.
Brazilian authorities have said they'll take another look at the case.
Gatti's friends and family have testified Rodrigues was a spoiled, money-obsessed and foul-mouthed wife who verbally and physically abused her husband and made frequent slights against his family.
Rodrigues' lawyers have countered that Gatti was a heavy drinker, spender and partier, which was the main cause of friction between the couple.
Rodrigues is expected to take the stand next in the civil trial.
Documents deposited this week show that Gatti's fortune is far less than the $6 million figure being bandied about at the beginning of the trial.
In fact, Gatti's worth between the U.S. and Canada is estimated to be about $3.4 million.