As NPR's Sylvia Poggioli reported in October, Caruana Galizia's independently operated website "often drew more readers than the total circulation of Malta's newspapers".
Her son Matthew Caruana Galizia, who works for the International Consortium of Journalists that released the Panama Papers, has compared the political situation to a "mafia state".
Ms Caruana Galizia, whose reporting focused heavily on corruption on the European Union island nation, was killed when a bomb destroyed her vehicle as she was driving near her home.
Just before her death, Caruana Galizia, 53, had posted on her closely followed blog, Running Commentary, that there were "crooks everywhere" in Malta.
Two more people have been arrested since Prime Minister Joseph Muscat's press conference this morning.
"Caruana Galizia's critics called her a force of nature who had on at least one occasion nearly single-handedly brought the government to collapse".
Caruana Galizia accused senior figures in both government and opposition of corruption and money laundering. Muscat easily won reelection. He was not comforted by vows from Maltese authorities that they would do their utmost to investigate the assassination.
Now, after the first major break in the case, distrust continues to shadow the investigation.
He said that Muscat could also choose to inform the room whether the sensitivity of the Caruana Galizia family was respected in the way they were informed about the developments.
"I think today we saw a very importance development in this case", Muscat said, "but we need to wait for the process to be concluded before we can give all the information - something which I am not at liberty to do now, so as not to prejudice the case".
"Last month, her family had alleged that Farrugia had divulged confidential information that could hamper the investigation".
Malta's PM says eight people have been arrested over the killing of blogger Daphne Caruana Galizia.
Muscat said earlier the suspects had been trailed for some time before the arrests were made.
The investigation appeared to be continuing, as police and armed forces had cordoned off an area in Marsa, a small town close to Valletta, the capital.
A court hearing has been scheduled for Tuesday, when the police can officially file charges and the suspects can enter a plea.