VALLETTA, Malta -- The sons of slain investigative journalist Daphne Caruana Galizia have called on the Maltese prime minister to resign.
In a Facebook post Thursday, they said Joseph Muscat should take political responsibility for "failing to uphold our fundamental freedoms."
The sons, Matthew, Andrew and Paul Caruana Galizia, said they weren't endorsing Muscat's call for a reward to lead to their mother's assassins, saying "we are not interested in justice without change."
"We are not interested in a criminal conviction, only for the people in government who stood to gain from our mother's murder to turn around and say that justice has been served," they said.
Caruana Galizia, a harsh critic of Muscat's and who reported extensively on corruption on Malta, was killed by a car bomb on Monday.
Her sons wrote that identifying their mother's assassins was not enough. Corruption on the Mediterranean island nation also needed to be rooted out, they said.
Muscat has denounced the assassination, and has proposed a reward to find her killers.
On Thursday, some 200 journalists held an event in support of the slain journalist.
A group representing journalist - the Institute of Maltese Journalists - has filed a court case seeking to ensure source confidentiality on all data that is lifted from Caruana Galizia's computers and mobile phones during the investigation.
Investigators, meanwhile, were looking at similarities with other car bombings in Malta over the last two years -- six in all including Caruana Galizia's. None have been solved.
Former police commissioner John Rizzo told the Malta Independent that it appears that mobile detonated explosives were used in each of the six bombings since the start of 2016, which caused four deaths and two serious injuries. The previous victims were all known to police, the paper said.
"Very few people could construct such a bomb. Instructions may be obtained online but building such a device would still require a certain degree of skill," Rizzo said.
Investigators haven't publicly identified which explosives were used in the journalist's murder, but experts say any military grade explosives, like Semtex, are not available in Malta and would have had to be brought in from abroad.
Muscat defended the failure to solve the rash of car bombings as he left parliament Wednesday evening. Including the last six, there have been over 30 in the last 15 years on the island.
"I will continue to defend the institutions and I am a firm believer in the institutions," he said.
