A German consular officer was arrested in Rio de Janeiro after the death of his husband.
The man's body had multiple injuries that indicated an act of violence, senior investigator Camila Lourenço said on Sunday.
According to media reports, the German consular officer and his Belgian husband had been married for over 20 years.
The consulate employee first called for an ambulance himself because his husband suddenly felt bad and fell.
He also took sleeping pills and drank a lot.
However, investigators later discovered traces of blood throughout the apartment in the Ipanema district.
After the autopsy, police assumed a blow to the back of the head resulted in death.
The German Consulate General in Rio de Janeiro initially did not comment on the case when asked.
The Foreign Office said the German Embassy in Brasilia and the Consulate General in Rio are in close contact with the authorities investigating the case.