Police in Brazil hope the man they arrested in Rio de Janeiro for the alleged murder of a Brazilian executive in Sydney will be tried in Brazil and, if convicted, serve his sentence in one of the country’s jails.

The body of Cecilia Haddad, 38, was found in a river on 29 April, the same day her former boyfriend Mário Marcelo Santoro, 40, landed in Rio de Janeiro.

Prosecutors charged the Brazilian national with murder on Thursday.

“She was asphyxiated by the someone squeezing the neck and killing her,” said Fabio Cardoso, the head of Rio police’s homicide department. “Santoro was charged for Cecilia’s homicide.”

Santoro was arrested on Saturday at the home of an aunt in Botafogo, a middle-class area of the city.

Facebook Twitter Pinterest Mário Marcelo Santoro was arrested on Saturday at an aunt’s house. Photograph: Facebook

Santoro told a lawyer he was innocent, according to a report in the Brazilian newspaper O Globo. Cardoso said conversations with Santoro on Saturday were informal.

He added that police had requested details of the investigation from their Australian counterparts and Interpol but had so far not received a reply.

“We hope the Australian police supply all the information that we have requested so he can be judged and, if condemned, serve his sentence here in Brazil,” he said, adding that the crime was very violent, very serious, very cruel”.

Haddad had lived in Australia for a decade after moving to Perth with her then husband, Felipe Torres, and worked in mining and logistics. She relocated to Sydney in 2016 after the couple broke up and later began a relationship with Santoro, whom she had known since they both studied at Pontifical Catholic University of Rio de Janeiro, Cardoso said. The couple had been together for around a year and lived together but broke up soon before her death.

Haddad had been working as a disability support worker at a company called Hireup. She and Santoro were also partners in a company called D.Care registered at her home address in Sydney. She was last seen at a barbecue in Sydney on 27 April, speaking to friends the next morning. Her body was found in Lane Cove river on 29 April – that same day, Santoro passed through immigration at Rio’s Galeão airport at 5.34pm.

Santoro had been unable to accept her ending their relationship, Cardoso said.

On Friday police went to Santoro’s parents’ home on the Atlântica Avenue in Copacabana and other addresses before returning the next day to an aunt’s house where they arrested him.

If convicted, Santoro could be sentenced to 30 years for murder and another three for hiding the body, Cardoso said. Cardoso said he believed Brazilian prison conditions are “much worse” than those in Australia.

Haddad’s brother João Müller Haddad welcomed the news.

“I don’t know if it was a relief because my sister will not come back but we have the feeling that justice is starting to be done,” he said. “We are very impressed with the efficiency of the Australian police as much as the Brazilian police.”