The police are to press charges against brothers Robert and Adrian Agius, their associate Jamie Vella, and George Degiorgio late on Wednesday over their alleged involvement in two murders.
Poice Commissioner Angelo Gafa' confirmed at a press conference that the four men will be arraigned over their alleged involvement in the murders of journalist Daphne Caruana Galizia in 2017 and lawyer Carmel Chricop in 2015.
The Aguis brothers, known by their family name Ta' Maksar, and Vella are likely to be charged with having supplied the bomb used to kill Caruana Galizia in October 2017.
All three men, who were previously known to the police, were arrested in a police operation on Tuesday.
Prosecutors are also expected to press separate charges against Degiorgio, known as Iċ-Ċiniz, concerning the 2015 murder of Chircop.
Chircop, 51, was gunned down inside a garage complex in Birkirkara on a Thursday morning in October 2015, as he was heading to work.
He was shot four times in the upper body and died on the spot.
Degiorgio is one of three men charged with the murder of Caruana Galizia, along with his brother Alfred, known as il-Fulu, and Vincent Muscat.
Muscat pleaded guilty to that crime on Tuesday, as part of a deal struck with the authorities. He was sentenced to 15 years in prison and ordered to pay court costs of €42,000.
Muscat, known as il-Koħħu, was also given a presidential pardon this week in exchange for information about the murder of Chircop. He has turned state witness and provided evidence to the authorities.
The pardon was published on Wednesday.