One of three men accused of planting and detonating the car bomb that killed the anti-corruption journalist Daphne Caruana Galizia in 2017 has pleaded guilty to the crime and been sentenced to 15 years in prison. Vincent Muscat is the first person to be convicted of the killing, which has embroiled Malta’s ruling Labour party in political scandal and led to the resignation of its prime minister in late 2019. In a day of dramatic developments, police made three new arrests, apprehending the brothers Adrian and Robert Agius, and their associate Jamie Vella, on suspicion of having supplied the bomb used to murder Caruana Galizia. News of the arrests emerged just after Muscat’s lawyer announced in court that his client was ready to change his plea to guilty. Muscat, who is believed by police to have acted as a hitman in a contract to kill the journalist, is reported to have negotiated a more lenient sentence in exchange for supplying state prosecutors with information on others involved. He has also been granted a presidential pardon to help shed light on an entirely separate case – the 2015 murder of a lawyer, Carmel Chircop. Malta’s prime minister, Robert Abela, and his cabinet approved the request for Muscat’s pardon on Monday. Chircop died aged 51, killed by gunmen on his way to work. The case has never been solved. In a statement to the court, a lawyer for Caruana Galizia’s family hailed Muscat’s conviction, saying “this step will begin to lead to full justice”. The journalist is survived by her widower and three sons. Their lawyer, Jason Azzopardi, said: “A person who has admitted his involvement in the murder of Daphne Caruana Galizia has denied her her right to life and has denied her her right to enjoy her family, including her grandchildren who were born after she was killed. “The macabre murder of Daphne Caruana Galizia was intentional and should have been prevented.” At a press conference on Tuesday evening, the prime minister confirmed Muscat’s pardon had been agreed after a recommendation in favour by the attorney general and the police commissioner. In statements posted on Twitter, Abela claimed the conviction was proof of “the effectiveness of the country’s institutions”. “Today’s events have edged us closer to establishing the truth in this dark chapter for the country and the Caruana Galizia family,” he added. Opposition leader Bernard Grech was critical, saying the state had failed in its duty to safeguard the victim. Caruana Galizia was one of Malta’s most prominent journalists, known both as a columnist and for her scoops on political corruption. She was aligned with the opposition Nationalist party. “Today’s developments confirm one thing,” Grech tweeted. “Had our institutions not been hijacked by those seeking to protect themselves, Daphne Caruana Galizia would still be alive.” Muscat has admitted to all six charges in the Caruana Galizia case: wilful homicide, causing an explosion which led to the death of a person, illegal possession of explosives, conspiracy to carry out a crime, promotion of a group intending to carry out criminal acts and participation in such a group. He could be released as early as 2027, with reductions to his sentence for time already served and good behaviour. Evidence that he provided in hours of police recordings is expected to assist in prosecuting others. Arrested in December 2017, Muscat was charged alongside the brothers George and Alfred Degiorgio, who are still denying any involvement. A third man, Melvin Theuma, has secured a presidential pardon. He claims to have acted as a middleman, hiring and paying the Degiorgio brothers to carry out the killing on behalf of the Maltese property and energy tycoon Yorgen Fenech. The businessman, who was one of many targets of Caruana Galizia’s investigations, is currently in custody, charged with masterminding the crime. He denies involvement in the murder. The guilty plea was entered just after 1.30pm on Tuesday, with Muscat standing in the dock in a heavily guarded courtroom, while the Degiorgio brothers looked on from the benches behind him. Judge Edwina Grima sentenced him to 15 years in prison shortly afterwards, and he was ordered to pay €42,930 (£37,000) in costs to the court. The Agius brothers, and Vella, were arrested along with 10 others during police raids in December 2017. However, no charges were brought and they were released without charge. Last October, newspapers in Malta reported that a member of Muscat’s family had been offered hush money by Robert Agius and Vella in exchange for his silence. The approach was corroborated on behalf of his client by Muscat’s lawyer Marc Sant, who said the money had been refused. Just before her death, Caruana Galizia had received a leak consisting of hundreds of thousands of emails and documents from a company partly owned by Fenech, which had secured a lucrative government contract to build a power station. Police told a hearing in the case against Fenech last August that they believed the journalist was killed for what she was preparing to reveal about the power station, operated by a company called Electrogas.