The Mediterranean country observed a national day of mourning in her honor and has offered a 1-million-euro (1.19 million US dollar) reward for information about her murder.
She ran a popular blog in which she relentlessly highlighted cases of alleged high-level corruption targeting politicians from across party lines, including her island nation's links with the so-called Panama Papers document leak.
Caruana Galizia made plain she didn't trust the island's police or judiciary to adequately investigate numerous wrongdoings she alleged.
She was killed as she was driving near the village of Bidnija in northern Malta.
She died in the blast that wrecked her auto as she was leaving her house, throwing debris and body parts into a nearby field.
Eight Maltese citizens were arrested because of "reasonable suspicion" for their involvement in Caruana Galizia's killing, Muscat told reporters at a news conference. Our country deserves justice, ' he said in a televised statement at the time, in which he called for national unity.
Her murder raised concern within the European Union about the rule of law in Malta, and many saw it as an attack on independent media.
Ms Caruana Galizia was named by Politico magazine among the 28 Europeans who are "shaping, shaking and stirring" Europe.
'The only remedy for anyone who felt slandered was through the courts'.
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".
An ambulance and police vehicles are parked along the road where a auto bomb exploded killing investigative journalist Daphne Caruana Galizia, in the town of Mosta, Malta.
They have all denied the accusations and she had been hit with 36 libel suits in the nine months preceding her death. Muscat easily won reelection.
'There are crooks everywhere you look now. "The situation is desperate".
In another entry a year ago, she wrote: 'Malta's public life is afflicted with dangerously unstable men with no principles or scruples'.
He later tweeted that two others had been arrested with police sources saying they were also Maltese. It gave no further information.
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