Facing pressure from the European Union to make progress in the investigation of the car bomb killing of journalist Daphne Caruana Galizia, Malta announced Monday that 10 people had been arrested in connection with the crime.

The detentions were the first outward signs that authorities, whose inquiry into the killing has been dogged by accusations of incompetence and political meddling, were any closer to finding those responsible.

The family of the murdered journalist took no comfort from the detentions, complaining in a statement that they had been announced by the prime minister instead of the police, a blurring of responsibilities that, along with the swift leaking of the names and mug shots of suspects to local news media outlets, “prejudice the integrity of the investigation.”

Expressing concern that the authorities may “also be leaking information to other suspects, some of whom could be in or close to the government,” the family said, “None of the developments in the investigation or its handling by the Malta Police have served to reassure the family that real justice is within reach.”

The family said it was “concerned that a number of people who could be implicated continue to receive political cover for crimes they are widely reported to have committed.”

The killing of Caruana Galizia in October stunned residents of the Mediterranean island, where she had exposed startling levels of corruption in high places. It led to calls in the European Parliament for Malta, which joined the bloc in 2004, to be sanctioned for violating fundamental rights by failing to guarantee the rule of law.

All of those detained were Maltese citizens and were picked up in raids on three locations across Malta, according to a government official who spoke on condition of anonymity. Most of the suspects were already known to the police in connection with other crimes, including murder, the official said.

Joseph Muscat, Malta’s prime minister, said in separate statements Monday that the suspects had been rounded up in operations involving the police, army and intelligence services. Officials said the operation was continuing and could lead to further detentions.

Investigators have 48 hours to question the suspects before deciding whether to prosecute them, Muscat said, offering no further details, including what charges might be filed.

The detentions came three days after members of the European Parliament completed a visit to Malta to examine its justice system. They voiced concern about a “culture of impunity” on the island, a problem that Caruana Galizia had put at the centre of her online blog, Running Commentary, and in a column in The Malta Independent newspaper.

Sven Giegold, a member of the European Parliament delegation, said in a statement Friday that the group had arrived on the island “seriously concerned over the rule of law in Malta and left even more worried.”

“The police and the attorney general have demonstrated an unwillingness to investigate and failure to prosecute corruption and money laundering,” he added.

The delegation’s complaints added to momentum in Brussels for action against Malta under what is known as Article 7, a previously unused provision in EU law that, in extreme cases, allows a country to be stripped of its voting rights and subjected to other punishments. That is unlikely to happen to Malta in the short term, but even the start of a full formal investigation by the European Commission, the bloc’s executive arm, would be a severe blow.

Michael Farrugia, Malta’s minister of home affairs, said on Twitter that the investigation had involved “foreign experts,” but he did not specify their nationalities. The FBI; Europol, a European police organization; and officials from the Netherlands have been assisting Maltese investigators, but the island’s police commissioner has said that those agents were only providing technical support and were not involved in steering the investigation.

The death of Caruana Galizia, 53, prompted protests attended by thousands of people. She was killed as she drove near her home in a rented car. The blast was so powerful that the police took four days to collect body parts and wreckage.