The Brazilian legal team defending Mario Marcelo Santoro will push to have the murder charge against him thrown out of court.

Lawyer Mauricio Eduardo Mayr has spent the last few weeks pouring over the Rio de Janeiro Homicide Police case against Santoro, claiming there is no solid evidence.

The Brazilian national is charged with killing his former girlfriend, 38-year-old Cecilia Haddad in Sydney in April this year.

Santoro's lawyers claim his return to Brazil at the same time Ms Haddad's body was found in Sydney was a bad coincidence. (Supplied)

Ms Haddad was also Brazilian-born, but had been living in Australia for more than a decade.

The defence confirmed today it will move for the case to be dismissed by a judge in Brazil, due to a lack of evidence.

"Since we don't have knowledge of the evidence that was produced in Australia, only a police report that was collected informally, we don't have CCTV, exams, nothing," Mr Mayr said through a translator.

Santoro, 41, has been in custody in Brazil since his arrest in July this year.

It's alleged he fled Sydney on the morning of April 29, 2018; the same morning Ms Haddad's body was found by kayakers in the Lane Cove River.

He was later seen on CCTV arriving at Rio de Janeiro International Airport.

In documents filed in Rio de Janeiro's Court of Justice, the Prosecutor’s Office alleges Santoro fled to his home country in an effort to circumvent the application of Australian law.

Mario Marcelo Santoro's lawyers are pushing to have the murder charge thrown out due to lack of evidence. (9news)

"There is no doubt, in my opinion, that Mario Marcelo sought refuge and impunity in Brazilian territory, knowing from here he could not be extradited, and thus to avoid the actions of the Australian police and justice," Deputy Police Delegate, Mauricio Luciano de Almeida e Silva, writes in the court documents.

However, Marcelo's legal team has explained the timing of his arrival in his home country as " just a bad co-incidence."

His legal team claim he left Australia in a hurry on the same morning his ex-girlfriend was found dead because his father had "major cardiac issues" in Rio. They also say Santoro may not have foreseen that Brazilian Homicide Police would conduct their own investigation into Ms Haddad's death.

Under Brazil's extraterritoriality laws, Santoro is subject to the laws of his homeland, even though the crimes were allegedly committed abroad.

Santoro is charged with the murder of his ex-girlfriend, as well as hiding her body.

He is due to face trial in Brazil, and if found guilty will serve time in a Brazilian prison.

Santoro will likely face court in Brazil, with authorities all but ruling out sending him back to Australia. Picture: 9NEWS (9news)

It's alleged he strangled his ex-girlfriend in the kitchen of her Ryde apartment sometime between April 28 and April 29, 2018, before dumping her body.

A pre-trial hearing in Rio yesterday heard he allegedly gave an "informal confession" during which he told police he wrapped the body in a blanket or mattress and used Ms Haddad’s car to take her body to the river.

Santoro's lawyer Mauricio Eduardo Mayr claims the confession cannot stand up in court.

He said it was during an off-the-record conversation, accusing the Rio homicide police of refusing to call a lawyer for Santoro after his arrest.

The murder charge Santoro faces goes further, and falls into the category of "femicide"- the killing of a woman because she is a woman.

Femicide is a new law in Brazil, introduced in 2015, in an effort to combat escalating rates of domestic violence. If convicted, it means a much harsher sentence.

Months after the death of Ms Haddad, Santoro was found at his sister's apartment in Rio de Janeiro. He was arrested and has been in custody since July 7 while police in Australia and Rio build the case against him.

Brazilian Homicide police are relying on text messages sent via WhatsApp, between Marcelo Santoro and his alleged victim's family, and also between Ms Haddad and her family, where she expresses concern about the hostile behaviour of Santoro after she tried to break up with him.

On the 12th of April, two weeks before her death, Ms Haddad messaged her brother João Haddad to tell him she was staying at a friend's place, away from Santoro.

CECILIA: "Hi. I drove back to Sydney and I'm here at Anna's house, from my old job. I'm going to sleep here with her. It's ok."

JOÃO: " It's okay. Take care. Stay calm. He should stay at his friend's house, not you."

João also directs his sister to turn off the WhatsApp setting where a user can see if another user is online, or has read a message.

The body of Ceclia Haddad was found in Sydney's Lane Cover river in April. (9news)

Ms Haddad replied that she already took that precaution and that she has also blocked Santoro from contacting her on the app.

Five days before her death, on April 24 in another message from Cecilia to her brother, João she says that "Poca" (Santoro's nickname after the character Pocahontas) is upset and constantly calling her ex-husband, Felipe.

CECILIA: "BTW, Felipe wrote to me now to say that Poca does not stop disturbing him... calling and crying 10 times a day. Wow! What a mess".

The prosecution alleges Ms Haddad had told her family she had made repeated attempts to end the relationship with Marcelo, and had been suffering "psychological violence."

Ms Haddad’s stepmother, Andrea Haddad, told Brazil police Cecilia asked Marcelo to leave the house and take his belongings, but he refused.

Mrs Haddad says on April 13, 2018 (two weeks before Ms Haddad’s death) her stepdaughter called her to say she was leaving her house until Marcelo moved out.

In José Haddad's police statement he said on April 27, two days before his daughter's body was found, she phoned him twice, saying she was afraid of seeing her ex-partner at her home.

He said he messaged her a number of times on April 28, with no reply. On April 29 he was contacted by Ms Haddad's ex-husband to tell him his daughter's body had been found in Sydney's Lane Cove River.

In the month prior, Santoro was painting a different picture of the relationship breakdown.

On March 11 2018, he contacted Jose Haddad.

MARCELO: "It is not working anymore, I cannot continue with your daughter, I tried and I am still trying but she is too moody, individualist and the worst, liar... Let us have a man to man talk."

He sent a similar note to Ms Haddad’s brother, João.

Text messages detectives suspect were written by the accused, using the alleged victim's phone after her death, were included in court documents lodged by Brazilian police.

According to the documents before the judge, Ms Haddad's phone "had the mechanism of unlocking with Touch ID" i.e. by the fingerprint of the owner.

Police suspect Santoro used Ms Haddad's finger to unlock her phone and send messages to Anna, a good friend in Australia, and to her mother.

"It is suspected that the accused has used the finger of Cecilia, already dead, to send messages to her best friend in Australia and to her mother in Brazil," court documents allege.

The message sent on April 28 from Ms Haddad\'s phone to her mother, appears to refer to Marcelo Santoro's daughters in Brazil.

"Poca (Marcelo) did not come here and left the key. He is returning to Brazil on Tuesday, he could not stand the homesickness of the girls."

Santoro's legal team have dismissed the message trails as "chit chat, and gossip."

They claim they didn't come from police forensic examinations and rather selected messages were handed over Ms Haddad's family, with "gaps" in the timeline.