The German consul in Rio de Janeiro Uwe Herbert Hahn was arrested on Saturday in connection with the death of his Belgian husband, police said.
Hahn said that his husband, Walter Biot, had died on Friday when he fell from their apartment in the Ipanema neighbourhood after suffering a sudden illness.
But police arrested him on suspicion of murder after their forensics found bloodstains in the apartment, and the autopsy of Biot's body showed multiple wounds.
"There are indications of recurrent blunt force injuries, and I can say for sure that the victim was beaten," police investigator Camila Lourenco told reporters.
The German Consulate in Rio did not immediately respond to a request for comment.
According to Brazilian news portal G1, the couple had been together for 23 years. Biot was 52.