Anna-Maria Gatti, the sister of slain Montreal boxer Arturo Gatti, says she never trusted her sister-in-law, and believes she was responsible for his murder.

In a telephone interview, Gatti told CTV News she was immediately suspicious when Amanda Rodrigues, 23, called her in Florida to tell her about her brother's death.

"She said, 'Something bad happened.' I said, 'What happened Amanda?' She said, 'Arturo died.'"

Officers believe the 37-year-old boxer was strangled to death after he fell into an alcohol-induced sleep. Gatti was found dead early Saturday morning at a seaside resort in northeastern Brazil.

Rodrigues, who is Brazilian, has been taken into custody and formally accused. Officers have thus far stopped short of laying charges, however, as they search for more clues.

Meanwhile, Anna-Maria Gatti said she suspects that Rodrigues had been plotting to kill her brother so she could get a hold of his multi-million dollar fortune.

"I think she was planning what she had to do, and she kept my brother from us because we would have seen what was going on...She always provoked fights and she always said, 'I'm gonna kill you, I'm gonna kill you," said Gatti, recalling that the entire family had warned Arturo to stay away from Rodrigues.

"My mother told him to leave her. The only reason that he didn't want to leave her was the boy," she added, referring to the couple's infant son.

Jeremy Filosa, a broadcaster and friend of Gatti's, told CTV News everyone in Gatti's circle of friends knew there were serious problems in the relationship.

"She vandalized his car, she threw stuff at him. At one point, she gave him a black eye. People were making fun of him, saying, 'Here's a world champ, and his girlfriend is beating him up,'" Filosa said.

Yvon Michel, a local boxing promoter and also a friend of Gatti's, agreed that the couple's two-year relationship was a tumultuous one.

"We kind of believe that it's possible that his wife has been involved (in his death)," he said.

Gatti's family is heading to Brazil to reclaim the former Canadian boxing champ's body, while funeral arrangements are being made in Montreal.

With files from CTV.ca News Staff