SBS News understands police in Rio de Janeiro have arrested Mario Marcelo Santoro, the man suspected in the murder of Cecilia Haddad.
Ms Haddad's body was found in Sydney's Lane Cove river on April 29.
It's understood Santoro was arrested about 4.30am Sunday (AEST) after a warrant was issued for his arrest.
He is being held at the Homicide Squad headquarters in Rio de Janeiro.
He was considered a fugitive in both Australia and Brazil.
Santoro, Haddad's ex-boyfriend, is the man NSW police believe to be a prime suspect in the murder investigation.
It's understood their relationship had ended weeks before her death.
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The 40-year-old engineer is believed to have left Australia for Rio de Janeiro on the same weekend that Haddad's (a Brazilian national) body was found.
“At the request of the Homicide Division and favourable manifestation of the MP, the state court of Rio de Janeiro decreed, early yesterday evening, the arrest of the indicted Mário Marcelo Ferreira dos Santos Santoro," the Homicide Division said in a statement on Saturday.
Brazil's Homicide Division is leading the investigation since Haddad's family reported her death in May.
Police have scoured Santoro's home in Rio de Janeiro as well as the home of his parents in Copacabana.
The arrest comes a week after Australian police and Interpol issued warrants for Santoro's arrest.
There are concerns Santoro will never be extradited to Australia to face charges because of Brazilian laws and customs.
