The remains of Cara Maria Burke, 17, were discovered beneath a bridge in the central city of Goiania.
Her boyfriend, Mohamed D'Ali Carvalho Santos, 20, was said by police to have confessed to killing her, cutting up her body and throwing her remains in a river.
'He did not show any regret,' claimed police chief Jose Maria da Silva. The victim was said to have travelled to Brazil to be with her boyfriend after meeting him in London.
They had lived together in a flat for three months but recently split up.
According to police, the killing was sparked when the teenager spurned her lover's marriage proposal.
However, other reports suggested she had threatened to tell his family he was a cocaine-addict drug dealer.
Miss Burke's torso, which was found on Tuesday, was identified by a distinguishing tattoo. Police are still searching for her head and limbs.
Mr da Silva said Santos went to a party after stabbing her and putting her body in his bath. He left to dispose of the body but returned to the party. He was also said to have photographed her remains on his mobile phone.
It was unclear last night whether the alleged killer was Brazilian or a British citizen of Turkish descent.
Police said Miss Burke's family in London had been told of her death.