Italian police are investigating a leaked photo of a blindfolded American teenager who is accused of killing an officer in Rome.
The photo of murder suspect Gabriel Christian Natale-Hjorth, 18, was shown by Italian media on Sunday.
Mr Natale-Hjorth and his friend, 19-year-old Finnegan Lee Elder, were arrested on suspicion of killing police officer Mario Cerciello Rega on Friday.
Rega, 35, was stabbed to death in the Prati neighbourhood of Rome.
He was allegedly knifed eight times after he investigated a drug deal gone wrong involving the teen suspects.
Police have alleged that Mr Natale-Hjorth and Mr Elder, both students from San Francisco, California, "confessed to their guilt".
The picture of Mr Natale-Hjorth, showing him blindfolded with his head bowed and hands restrained behind his back, was taken after their arrest.
It was leaked to Italian newspaper, Corriere della Sera, whose article about the picture likened it to the treatment of prisoners at the US military detention camp Guantánamo Bay.
Italy's military police, the Carabinieri, has sought to distance itself from the leak of the photo and has launched an investigation.
"This is an unacceptable episode and should be treated as such," commander general of the force, Giovanni Nistri, told Corriere della Sera.
Police commander Francesco Gargaro said the blindfolding of a suspect is "illegal", telling the Associated Press that the officer responsible did so by "mistake".
"To those who complain about the blindfolding of a person arrested, I remind them that the only victim to cry for is a ... Carabinieri... who died while doing his job, killed by people who, if guilty, deserve to spend their life in prison," Mr Salvini tweeted.