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RIO DE JANEIRO — Police in Brazil believe that Greece's ambassador to the country was killed by his wife's lover under her orders in a house in the Rio area and have detained three suspects, authorities said Friday.

Ambassador Kyriakos Amiridis went missing on Monday in Nova Iguacu, a city just north of Rio de Janeiro, where the ambassador had been vacationing. The couple lived most of the time in the capital of Brasilia.

On Friday, police investigator Evaristo Pontes Magalhaes said that 29-year-old police officer Sergio Gomes Moreira Filho had confessed to killing Amiridis, alleging self-defense.

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Investigators said Filho knew Amiridis, who wasn't aware of the affair he was having with the ambassador's 40-year-old wife, Francoise Amiridis.

Magalhaes said Filho's cousin, Eduardo de Melo, acknowledged taking part in the killing as a lookout. The cousin accused Francoise of offering him the equivalent of $25,000 to participate.

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Francoise has denied that she was involved in the plot. According to Magalhaes, Francoise said she couldn't stop Filho from killing her husband and insisted she was not at home at the time of the crime.

But the police investigator said in a press conference late Friday that the "evidence clearly puts the ambassador's wife as a co-author of the crime."

He said Francoise started plotting with Filho to kill the ambassador after the couple had a serious fight three days before Christmas.

"All our evidence suggests that her motivation was to use the financial resources left by the ambassador so she could enjoy life with Sergio."

"All our evidence suggests that her motivation was to use the financial resources left by the ambassador so she could enjoy life with Sergio," the police officer, Magalhaes said.

Magalhaes said a judge had ordered the temporary arrest of Francoise, Filho and his cousin.

The first signs that the ambassador had been murdered came late Thursday, when police found blood spots believed to be his on a sofa inside the house the couple kept in Nova Iguacu, where the wife's family lives.

Filho told police that he strangled the ambassador during a fight, but the blood evidence found on the scene makes his claim unlikely, Magalhaes said. Neighbors said they did not hear any shots in the house, leading police to believe the policeman stabbed Amiridis.

Magalhaes said the investigation also showed that Amiridis' body was removed from the house in a carpet at the same time that Francoise arrived with their 10 year-old daughter, who did not see the body of her dead father.

Police believe a body found in a burned-out car that Amiridis had rented on Dec. 21 belonged to the ambassador, but forensics experts are still working to confirm that it is him.

A burned car sits in the parking lot of the police station in Belford Roxo, Brazil,on Dec. 30, 2016. This burned vehicle, matching the description of the car rented by Greece's ambassador to Brazil Kyriakos Amiridis, was found with a body inside it in Nova Iguacu, but forensics experts have not yet identified the dead person. Leo Correa / AP

Brazil's government has offered its condolences to Greece over his death.

The Greek Embassy website in Brazil says Amiridis started his career as diplomat in 1985 in Athens and became Greece's top diplomat in Brazil in 2016.

He earlier was Greece's ambassador to Libya and worked as consul in Rio from 2001-2004.