Mr Gatti had retired from professional boxing in 2007
The former world boxing champion Arturo Gatti killed himself and was not murdered, say Brazilian investigators.
Mr Gatti was found on 11 July, in a hotel in north-eastern Brazil where he had been staying with his wife and son.
Shortly afterwards, his wife, Amanda Rodrigues, was arrested on suspicion of strangling Mr Gatti with the strap from her handbag.
A court has now ordered her release after the investigation found that Mr Gatti probably hanged himself.
Police at the time had said there were inconsistencies in the statement Ms Rodrigues gave to them and that she had not explained how she stayed in the hotel room for 10 hours after he died.
Her lawyer, Celio Avelino, said it "would have been impossible for her to suspend and hang a man of that size".
Mr Gatti was IBF super-featherweight champion in 1995 and WBC light-welterweight champion in 2004, and retired in 2007.
Gatti's career spanned 49 fights and he won 40 of them, 31 by knockout. He retired two years ago.