Rio de Janeiro police say they are interrogating the wife of Greece's ambassador to Brazil in connection with his disappearance.
Amiridis, 59, was last seen on Monday after leaving the house of friends of his Brazilian wife in the low-income suburb of Nova Iguaçu.
Globo TV has also reported that investigators suspect he was murdered at the behest of his wife and a police officer with whom she was having an affair.
Employees at the Greek consulate in Rio provided no information regarding Amiridis' whereabouts, while the Greek Embassy in Brasília did not comment on the case.
The ambassador's charred rental vehicle could be seen in the parking lot outside the police station, an AFP correspondent said.
Mr Amiridis spoke to his wife when he called her to tell her he was going out, but did not say where he was going. They are believed to often extort residents in exchange for keeping drug gangs from taking over the areas. The ambassador was reported missing by his wife on Wednesday.
But a source at the Greek foreign ministry confirmed that the auto was the one Amiridis had rented.
According to Brazilian police, the auto was rented by the ambassador who was visiting the city of Rio for the Christmas and New Year Eve holidays.
The diplomat previously served as Greece's consul general from 2001 to 2004 in Rio.
According to the Greek Foreign Ministry's website, Amiridis also was Greece's ambassador to Libya in 2012.
The ambassador and his wife had a 10-year-old daughter and resided in the Brazil's capital city, Brasilia.