VALLETTA (Reuters) - Maltese authorities have arrested a man suspected of acting as a go-between in the 2017 murder of journalist Daphne Caruana Galizia, and Prime Minister Joseph Muscat said he would recommend a pardon if the suspect reveals who ordered the hit.

Caruana Galizia, Malta’s most prominent anti-corruption journalist, was killed by a car bomb as she drove out of her home near the Maltese capital Valletta in October 2017 - a murder that shocked Europe and raised questions about the rule of law on the Mediterranean island.

Three men suspected of being the killers were arrested in December 2017, but the authorities have so far failed to determine who commissioned the murder.

The man arrested on Thursday, whose identity has not been revealed, is suspected of having acted as the intermediary between the person who ordered the murder and the men who carried it out.

He is seeking a pardon in return for revealing the mastermind, and wants the pardon to extend to other crimes.

He was arrested by Maltese police in association with Interpol, along with a group of other people suspected of belonging to a money-laundering ring. Muscat said he had signed a letter committing to a pardon once the suspect revealed what he knew and agreed to give evidence in court.

Speaking on the steps leading to his office in Valletta, Muscat said the decision to recommend the pardon was his own and he had not consulted the cabinet.

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“I promised I will leave no stone unturned (when Caruana Galizia was killed) and there will be no impunity to anyone, whoever he is,” he said.

Caruana Galizia’s family had no immediate comment

The Times of Malta, which first reported the arrest of the suspected middleman, said conditions for a pardon were the subject of intense discussions between police, the attorney general and Muscat. It said the man feared for his safety if he were sent to prison.

The newspaper said experts from European police organisation Europol had seized devices in the suspected middleman’s possession, after receiving the go-ahead from a magistrate.

Apart from the supposed middleman’s witness account, investigators are hoping Europol’s analysis of his devices will provide further evidence pointing to who may have been behind the killing, it said.

Muscat said on Sunday he had met the Caruana Galizia family and they had agreed on members of an independent inquiry and into whether the government could have prevented the murder.

The family earlier objected to two of three members of the inquiry nominated by the prime minister. They have now agreed on the appointment of two independent judges and another who is still serving. Terms of reference have not been published yet.