Arturo Gatti's aggressive style in the boxing ring earned him the nickname "Thunder".
The former junior welterweight champion retired two years ago, after a 16-year career.
Early Saturday morning, the 37-year-old was found dead at an upscale seaside resort in northeastern Brazil.
He was vacationing with his wife and infant son.
Friends and fellow boxers say they are dismayed by his death.
"It's very sad, it's... I've got goosebumps thinking about it," said Howard Grant. "It's very sickening this thing.
Grant, an Olympic boxer and gold medallist at the Commonwealth games, says Gatti was always entertaining in the ring.
"Arturo was a guy that was like a blood and guts guy. You know, he's losing, his eyes is shut, he's about to get knocked out and he throws one shot and he knocks the opponent out. And I think the kind of drama that he brought to boxing it hasn't been seen for a very, very long long time," said Grant.
Amanda Rodrigues, Gatti's 23-year-old wife, has been detained as a suspect by Brazilian authorities.
According to Brazilian police, Gatti was strangled with the strap of a purse, which was found at the scene stained with blood. Police also say Gatti sustained a head injury.
Rodrigues has denied being involved in her husband's death.
Those who knew the couple say there were signs their was trouble in the relationship.
Montreal boxing promoter Yvon Michel says Gatti and Rodrigues both had wild personalities, and that led to problems.
"Everybody around him also knew that it was also a difficult relationship with his wife," said fight promoter Yvon Michel.
"He was a genuine person who was living on the fast track, and wanted people around him, the same kind of people, and I believe his wife was also a little bit wild too, so not a good mix."
In the spring, Gatti was charged with assaulting Rodrigues, but the charge was later resolved out of court.
