Warrant out for Haddad's ex: report

NSW Police have reportedly secured a warrant for the arrest of the former partner of murdered Sydney woman Cecilia Haddad.

Mario Marcelo Santoro, who has not been charged and is currently in Brazil is a prime suspect in the death of Ms Haddad, 38, whose body was found in a river in April.

"NSW Police are not in a position to comment on the investigation at this stage," a spokesperson said in a statement on Wednesday.

Australia and Brazil have a long-standing extradition treaty that would nominally pave the way for Mr Santoro to be brought back to Australia.

However, the process could be complicated because Brazilian generally does not act upon orders for a citizen to be extradited to face alleged offences committed in foreign countries on constitutional grounds.

"The Australian government does not disclose whether it has made, or intends to make, an extradition request to a foreign country until the person is arrested or brought before the court in a foreign country," the federal Attorney-General Department said in a statement.

Kayakers discovered Ms Haddad's fully-clothed body in the Lane Cove River near Woolwich on Sunday, April 29, about the same time her former live-in lover Mario Marcelo Santoro flew back home to Rio de Janeiro.

Investigators confirmed in May that Ms Haddad had asked Mr Santoro to move out of her Ryde apartment, in Sydney's northwest in the weeks before her death.

Brazilian-born Ms Haddad arrived in Australia more than a decade ago and had moved to Sydney in 2016 where she worked in mining and logistics.