Greece's ambassador to Brazil was killed at the home his wife kept in the Rio de Janeiro area, police said.
Kyriakos Amiridis went missing on Monday in the city of Nova Iguacu, 25 miles north of Rio de Janeiro.
Greece's embassy in Brasilia said the ambassador had been on holiday near Rio. The couple lived most of the time in Brasilia, the country's capital.
Rio de Janeiro police investigator Giniton Lages said blood thought to belong to the ambassador was found on a sofa inside the home of his Brazilian wife, Francoise Amiridis.
Mr Lages named the wife, along with another woman and two men, as suspects in the case.
A news conference is scheduled for later in the day.
Mr Amiridis' wife is being questioned at a police station in connection with her husband's disappearance. Authorities believe she had been having an extra-marital affair with a police officer.
Mr Lages said authorities believe the ambassador's body was taken from the house to a car that he had rented on December 21.
A burned vehicle matching the description of the rented car was found with a body inside it in Nova Iguacu, but forensics experts have not yet identified the dead person.
The Greek embassy website in Brazil said Mr Amiridis started his career as diplomat in 1985 in Athens and became Greece's top diplomat in Brazil in 2016.
He was previously Greece's ambassador to Libya and worked as consul in Rio from 2001-2004.