An independent inquiry in Malta into the murder of the anti-corruption journalist Daphne Caruana Galizia has found that the state had to bear responsibility after creating a “culture of impunity”.

The 437-page report, conducted by a team of judges and released on Thursday, said the state “failed to recognise the real and immediate risks” to the investigative journalist’s life and “failed to take reasonable steps to avoid them”.

Caruana Galizia was killed by a car bomb as she drove away from her home on 16 October 2017. Her death was met with outrage across Europe, and embroiled Malta’s ruling Labour party in a political scandal.

Prosecutors believe the businessman Yorgen Fenech, who had close ties with senior government officials, masterminded the murder. Fenech, who is awaiting trial for association to murder, denies responsibility.

Three men suspected of setting off the bomb were arrested in December 2017. One has since pleaded guilty as part of a plea bargain and is serving a 15-year jail term. The other two are awaiting trial. The self-confessed middle man turned state witness and was granted a pardon.

The inquiry, conducted by one serving judge and two retired judges, found that a culture of impunity was created by the highest echelons of power within the government of the time.

“The tentacles of impunity then spread to other regulatory bodies and the police, leading to a collapse in the rule of law,” said the panel’s report, which was published by the prime minister, Robert Abela. 

It was clear, the inquiry board said, that the assassination was either intrinsically or directly linked to Caruana Galizia’s investigative work.

The former prime minister Joseph Muscat resigned in December 2019 after Fenech’s arrest. He has never been accused of any wrongdoing. Media later also revealed close links between Fenech, ministers and senior police officers.

Muscat wrote on Facebook on Thursday that the report “unequivocally states that I was in no way implicated in the murder … It is to be noted that the inquiry found that the state had no prior knowledge of, or was involved in the assassination.”

The report’s conclusions do not oblige the government to take any action, but the opposition Nationalist party called on Muscat and Abela to shoulder their responsibilities.

“The state inquiry is clear: Daphne Caruana Galizia’s murder was enabled by the collective inaction of Joseph Muscat’s cabinet, many of whom still hold public office. Robert Abela must ensure that responsibility for this culture of impunity is shouldered,” the opposition leader, Bernard Grech, said in a statement.

Abela tweeted that the report “merits mature analysis beyond partisan arguments. Lessons must be drawn and the reforms must continue with greater resolve.”

In their report, the judges attributed indirect responsibility to Muscat for the circumstances leading to the murder, citing his failure to act against his chief of staff, Keith Schembri, and the former energy minister Konrad Mizzi over their secret companies, revealed in the Panama Papers, and their alleged links to 17 Black, a secret company owned by Fenech.

Muscat, Schembri and Mizzi have not faced any charges linked to Caruana Galizia and have publicly denied involvement. Schembri and Mizzi did not comment on Thursday’s report.

The report said decisions by Muscat had strengthened the culture of impunity in which people the assassinated journalist wrote about operated. 

Repubblika, a rule-of-law group that held daily public protests in the run-up to Muscat’s resignation, announced another protest outside the prime minister’s office for Friday evening.

The judges called for immediate action to rein in and regulate the links between politicians and big business. Their inquiry heard evidence from the police, government officials, the Caruana Galizia family and journalists, among others.

Caruana Galizia had led the Panama Papers investigation into corruption in Malta. A blogger whose posts often attracted more readers than the combined circulation of the country’s newspapers, she had been described before her death by the Politico website as a “one-woman WikiLeaks”.

In a statement, the Caruana Galizia family said: “The inquiry’s findings confirm the conviction our family held from the moment Daphne was assassinated: that her assassination was a direct result of the collapse of the rule of law and the impunity that the state provided to the corrupt network she was reporting on.

“We hope that its findings will lead to the restoration of the rule of law in Malta, effective protection for journalists, and an end to the impunity that the corrupt officials Daphne investigated continue to enjoy. Daphne and her work will live on in ensuring that the recommendations of this inquiry effect lasting change.”

The Daphne Caruana Galizia Foundation said the report was a landmark moment in the campaign to hold the state accountable for its obligation to protect journalists. “This is a historic opportunity to ensure real change for the safety of journalists and to a process of national healing following the traumatic assassination of Daphne Caruana Galizia,” it said.