The arrests came seven weeks to the day after the assassination of Daphne Caruana Galizia. They were the first known break in a crime that shocked Malta and motivated European Union officials to look into the EU island nation's laws and government.
Caruana Galizia, 53, was killed Oct. 16 when a bomb destroyed her car as she was driving near her home. Prime Minister Joseph Muscat, who was among the subjects of the late reporter's investigations, declined to say who the suspects were or why they were arrested.
Eight Maltese citizens were arrested because of "reasonable suspicion" for their involvement in Caruana Galizia's killing, Muscat told reporters at a news conference.
A little while later, Muscat tweeted that two others had been arrested. They also are Maltese, Home Minister Michael Farrugia said. Authorities did not release the names of any of the 10 suspects.
Explaining the reason for staying tight-lipped, Muscat cited concerns that divulging information could compromise the prosecutions. Farrugia said he wouldn't disclose anything because "I have been already threatened by legal action by the Caruana Galizia family."
The journalist's family alleged last month that Farrugia had put the investigation at risk by sharing confidential information with lawmakers. The minister brushed off the allegation, but the family said it was prepared to take legal action to prevent the government from sabotaging the case.
Caruana Galizia's family reacted angrily to how the arrests were announced on Monday, saying police should have informed them before the prime minister. They reiterated their skepticism that justice would be carried out, despite Muscat's public insistence that all would be done to find and punish the killers.
Muscat "appears to view the investigation into Daphne Caruana Galizia's assassination as a marketing exercise for his government and not as a contract killing, which has left surviving family members wondering what happened and how justice can be truly served," the family said in a statement.
They said they had already written to the police commission about "the constant stream of leaks which prejudice the integrity of the investigation," but never received a response.
The family contended the police had leaked information about the identities of seven suspects.
"It is important to ask whether they are not also leaking information to other suspects, some of whom could be in or close to government," the statement continued.
"The blurring of boundaries with the executive - and this in a case which has political implications - is disturbing," the family statement said. "When the handling of an investigation is not sound, it is difficult to have faith in its outcome."
The arrests coordinated among the Police Corps, the Armed Forces of Malta and the Security Services. The investigation appeared to be continuing Monday as police and military members cordoned off an area in Marsa, a small port town close to Valletta, the capital of Malta. Marsa is where most of the arrests were made.
Video released later by Maltese police showed officers and members of the security service and armed forces making some of the arrests. Some officers arrived in Marsa by boat and apprehended suspects in waterfront warehouses.
Maltese media, citing unidentified police sources, said two brothers were among the suspects. One of them was acquitted of a 2015 armed robbery charge for lack of sufficient evidence. The other has been charged with possession of unlicensed weapons and tools used to pick locks.
Investigators have 48 hours to question the suspects to decide whether to seek charges, in accordance with Maltese law.
A court hearing was set for Tuesday, when the police can officially file charges. The suspects then can either plead innocent or guilty. The magistrate will decide whether to set bail or remand them in custody.
Europol, the European Union's police agency, has sent a team of organized crime experts to help Maltese police investigate the assassination, joining the FBI and Dutch forensic experts.
Muscat told reporters Monday that when the evidence is compiled, during court proceedings "all the relevant information will be made public," including input from the FBI and European investigators, including from Finland's National Bureau of Investigation, as well as Maltese investigators.
Just before her death, Caruana Galizia, 53, had posted on her closely followed blog, Running Commentary, that there were "crooks everywhere" in Malta.
Malta has a reputation as a tax haven in the European Union and has attracted companies and money from outside Europe as well.
Last week, a visiting delegation of European Parliament lawmakers left the island expressing concerns over the rule of law in the country and issued a warning that the "perception of impunity in Malta cannot continue."
Low tax rates and a popular government program that allows wealthy foreigners to buy Maltese citizenship have made the country an attractive place for investment, financial and other companies. Authorities, including anti-Mafia investigators in nearby Italy, worry that Malta is eyed by criminals on the lookout for money-laundering schemes.
Caruana Galizia focused her reporting for years on investigating political corruption and scandals, and reported on Maltese mobsters and drug trafficking. She also wrote about Maltese links to the so-called Panama Papers leaks about offshore financial havens.
Many top officials had sued her over her reporting. Caruana Galizia made plain she didn't trust the island's police or judiciary to adequately investigate many of the wrongdoings she alleged.
Muscat said Monday of the slaying: "As I stated as soon as I learned about this barbaric act, we will leave no stone unturned to get this case solved."
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