Mario Marcelo Santoro, the man accused of murdering his Brazilian ex-girlfriend Cecilia Haddad in Sydney, spoke for the first time during a court hearing in Rio de Janeiro on Monday and told the court his trip back home to Brazil on the weekend of her death had been planned in advance.

But under direction from his lawyers, Santoro, 40, only answered questions from the defence, did not address the issue of his innocence or guilt, and declined to answer questions from the judge or prosecutors.

The Brazilian mining executive Cecilia Haddad, 38, was killed in April and her body was dumped in Sydney’s Lane Cove River.

Haddad and Santoro both studied at Rio’s private Pontifical Catholic University and he said they had briefly dated then before beginning a relationship years later in Australia. Santoro had been living with Haddad in Sydney when she was murdered but flew to Rio the weekend as her body was found. He was arrested in July and charged with femicide after allegedly choking Haddad to death.

As Brazil does not extradite its citizens he is being tried in Rio. He appeared in court at a pretrial hearing September but this was the first time he had spoken.

Reporters were only allowed to access the court after Santoro had begun talking. Speaking softly, handcuffed and wearing a white T-shirt and jeans, he contradicted Haddad’s ex-husband, Felipe Torres, who according to his lawyers had said in court he did not know the couple were together. “I said we were living together,” Santoro said. “He didn’t want to know, they were in the process of a divorce.”

Asked why Haddad had slept away from her apartment where Santoro was also living during the week, he said it was because she had a job 100km away and slept away two to three nights a week.

In the September pretrial hearing, her father, José Haddad, stepmother, Andrea Haddad, and brother, João Haddad, said she had been a happy, hard-working young woman who had entered an abusive relationship with Santoro, suffered “psychological violence” and was scared of his obsessive, controlling behaviour.

In October, according to SBS and a court release, Rita Maciel, a friend of Haddad’s in Sydney, told the court via video conference that Santoro could not accept the end of their relationship and that Haddad had lived in fear. Her mother, Milu Mueller, said she had been taking to her daughter on the phone when she heard a man’s voice she recognised as Santoro’s demanding she open the door. She had been unable to contact her daughter after that.

Santoro’s lawyers said evidence produced by Australian police and delivered to their Brazilian counterparts and prosecutors in Rio in November had not yet been attached to court documents and they had advised their client not to answer questions from judge or prosecution.

“We asked Marcelo to remain silent, to exercise the right to not make any declaration in the sense of responding to any questions by the judge or the accusation,” Mauricio Mayr, one of his three-man defence team told reporters. “There is nothing new in terms of documental evidence.”

Asked by his lawyer why he had flown back to Brazil the weekend Haddad’s body was found, Santoro said his father was sick with a heart condition and that he had arranged a holiday with relatives, himself and Haddad in Chile. From there, he and Haddad had planned to fly back to Australia, he said.

Mayr said his defence team had challenged the competence of the Rio de Janeiro state court to hear the case, arguing that it should come under federal justice. That would invalidate Santoro’s “preventative prison” order that kept him in custody and could even mean he might sit out the rest of the lengthy court and appeals process at liberty, he said.

“All the requests that are being made by Australia are going via the Foreign Ministry, and that’s why the defence believes that the competent judge would be federal,” Mayr said. “He would wait out the judgment of this process at liberty.”

The defence team also challenged the legality of an informal confession Santoro made to a police officer while in custody, outlined to the court in September by Fabio Cardoso, the head of the Rio homicide squad. Santoro did not repeat the confession in front of lawyers.

“There is no confirmation that it could have happened,” Mayr said.

Fabio Cardoso told the Guardian he defended the confession but admitted: “There is no recording, no confession signed by him.”

He said his squad’s research had shown that the case was in the right court of justice. “The state court has the competence to try this case,” he said.

Australian police officers had travelled to Rio last month and handed over their evidence, he said, following up with an email summarising evidence sent to the Rio state prosecutor.

The case will now continue next year when a judge will decide if it will proceed to a jury trial, according to Santoro’s lawyers. Rio state prosecutors did not immediately respond to questions.