Judge Patricia Acioli had implicated 91 police officers in murder cases before she was killed in August [EPA]

A court has ordered the arrest of a Brazilian police commander and seven other police officers on suspicion of murdering a judge who was investigating their connection to another killing, an official said.

Judge Patricia Acioli, 47, was shot on August 12 by masked assailants on motorcycles who intercepted her as she arrived home, in a crime that caused public outrage.

"The incarceration of Sao Gonzalo battalion commander, Lieutenant Colonel Claudi Luiz Oliveria, has been decreed, as has that of seven other police officers who worked with him," a spokesperson for the Rio de Janeiro courts told reporters.

Sao Gonzalo is a municipality near Niteroi where the judge, a mother of three, lived and worked across Guanabara Bay from Rio.

Brazilian newspapers Globo and Folha de Sao Paulo said Oliveira was suspected of ordering the judge's killing to cover up another murder by members of his battalion.

Acioli had been investigating the death of an 18-year-old youth who police said was killed in a clash in Salgueiro, a slum area in Sao Gonzalo.

Just hours before her death, Acioli signed warrants for the arrest of the police officers in Oliveira's battalion on suspicion of murdering the youth and then covering up the crime by falsely reporting the circumstances of his death, the reports said.

Prosecutors believe the police killed the judge to try to avoid prison for the youth's killing, without knowing that she had already signed the arrest warrants.

On September 12, the courts jailed three other police on suspicion of involvement in the murder.

Acioli was known as an uncompromising crime fighter whose investigations targeted police, firefighters and security guards with links to organised crime.

"Patricia received threats for at least five years. She was considered a hard-line judge, always giving the maximum penalty," her cousin, Humberto Nascimento, was quoted as saying at the time of her death.

She had drawn up a list of 91 police officers implicated in murders, and who are currently under investigation.

Source: Agencies