A bomb that killed a Maltese anti-corruption journalist was detonated by one of the suspects sending a text message from a boat, prosecutors believe.
Daphne Caruana Galizia’s car was blown up as she drove from her home on the island on 16 October.
The assassination sparked outrage in Malta and among many journalists and politicians in Europe and worldwide, who view it as an attack on free speech.
Three men, two of them brothers, were charged with her murder on Tuesday.
Seven other men were released on bail.
Police sources said it was suspected that George Degiorgio sent the text after getting a signal from his brother Alfred, who they think acted as a lookout.
A boat has been impounded and the sources say mobile phones have been recovered from the sea in Valletta harbour.
Vincent Muscat, 55, George Degiorgio, 54, and Alfred Degiorgio, 52, all deny murder.
They were also charged with manufacturing the bomb which killed the journalist, taking part in organised crime, as well as possessing explosives.
Caruana Galizia’s family have released a statement saying that she was not investigating any of the 10 men arrested.
Witnesses to her murder describe seeing two explosions coming from her car and the vehicle skidding down the road, before ending up on fire in a field.
Her son, Matthew Caruana Galizia, said he found his mother’s body in pieces.
Evidence suggests the bomb was placed in her rented car while it was parked in an alley outside her house.
The journalist’s articles probed issues such as government officials named in the Panama Papers leaks, Malta’s reputation as a tax haven, and links with Libya.
Malta’s prime minister, Joseph Muscat, often a target of Caruana Galizia’s articles, vowed no stone would be left unturned in finding the killers and has offered a €1m (£890,000) reward to bring her killers to justice.
A group of EU lawmakers who went to Malta on a fact-finding mission last week said there was a “perception of impunity” on the island.
The head of the delegation, Ana Gomes, said the murder “was aimed at instilling fear in everyone, especially those involved in investigating and prosecuting cases of money laundering and corruption”.