Just when it seemed that Brazil’s scandal-plagued political class could not be any less popular, the country is incensed at the revelation that its congress will soon include a man jailed for the sexual exploitation of underage girls.

Nelson Nahim, a politician from Rio de Janeiro state who is affiliated with President Michel Temer’s Brazilian Democratic Movement Party, was handed a 12-year sentence in 2016 for submitting a 15-year-old girl to prostitution/sexual exploitation, rape and intimidating behaviour.

As a “substitute” lawmaker for a coalition of parties, he will take the seat vacated by Brazil’s new minister of labour, Cristiane Brasil, when congress returns from recess next month, but he officially becomes a deputy when she takes up her new role next week.

Adding fuel to the fire, Brasil herself was in 2016 ordered to make payments to a former driver whom she had employed without proper papers. Brasil is also the daughter of a politician jailed in a previous scandal.

“It provokes nausea and vomit,” José de Lima, a retired Brazilian living in Florianópolis in the south of the country, wrote on a Facebook group page. “The current Brazilian congress will always be capable of getting worse.”

Documents submitted to court described Nahim, 60, as a regular client of a prostitution ring in the Rio town of Campos dos Goytacazes between 2008 and 2009, in which underage girls were kept behind bars and forced to consume drugs in order to have sex with clients. According to prosecutors, Nahim had sex with two 15-year-old girls at a country house he owned. He denies the allegations.

“There was a chain of sexual exploitation in Campos,” said Ludimila Rodrigues, one of a group of prosecutors who worked on the court case. “He was one of the clients of this network of prostitution.”

In 2016, Judge Daniela de Souza sentenced 12 of those involved to prison and two to open prison regimes. Nahim was handed 12 years but served four months before being released on appeal by a supreme court judge.

In a statement at the time, the court in Rio that sentenced Nahim highlighted his “relationship with a 15-year-old teenager known as ‘Barbie Girl’, with whom he had sexual encounters,” adding: “The teenager enjoyed differential treatment for being Nahim’s favourite.”

Nahim, who also sat briefly in congress as substitute for another lawmaker a year ago, said in a Facebook post that he would prove his innocence.

“I thank God and on assuming the mandate of a federal deputy I will fight for the population and show my innocence with documents,” he wrote.

Brazilian lawmakers are no strangers to controversy and have faced charges ranging from corruption to murder. One lawmaker, Celso Jacob, last year attended Congress on day release from prison, where he is serving a sentence for administrative fraud when he was a mayor.

Nahim is estranged from his brother, the former Rio state governor Anthony Garotinho, who was jailed with his wife, Rosinha, in November for electoral crimes, and briefly replaced Garotinho’s wife as mayor of Campos. The couple were later released.

Cristiane Brasil’s father, Roberto Jefferson, was also jailed for his role in the “Mensalão” vote-buying scandal, which almost brought down the leftist president Luiz Inácio Lula da Silva in 2005. Jefferson cried on discussing her appointment with reporters and said it had “rescued the family”.