A dramatic turning point could take place tomorrow as a key witness begins giving a sworn statement before the magistrate investigating Daphne Caruana Galizia’s murder.

Melvin Theuma’s testimony is likely to mount fresh pressure on Prime Minister Joseph Muscat to step down.

Theuma, the alleged middleman between the commissioners and the executors, has been given a Presidential Pardon on the Prime Minister’s personal recommendation – a decision Muscat took when Keith Schembri, who resigned on Tuesday, was still his Chief of Staff.

Since Theuma’s pardon was granted, prime suspect Yorgen Fenech requested his own pardon and reported Schembri for masterminding the assassination and trying to obstruct justice – including by offering Fenech a pardon in return for keeping quiet.

These claims today led to the arrest of Fenech’s doctor Adrian Vella who was allegedly used by Schembri to send messages to Fenech and may have been part of a plot to help Fenech escape the island a week before his arrest.

The question now is whether Theuma will name Fenech, Schembri, or both of them as the masterminds of the assassination, which took place on 16th October 2017.

Theuma has already contributed to the investigation through recordings found at his home which he allegedly took to protect himself after the murder took place. Sources say these recordings mostly incriminate Fenech.

However, Schembri is also named, sources close to the investigation have confirmed.

The mentions of Schembri in the recordings make it difficult for Theuma to leave the former Chief of Staff out of his testimony completely. These mentions also strengthen Fenech’s version of events that Schembri played a role in the murder and/or its coverup.

However, whichever way the testimony goes, Muscat is likely to suffer, primarily of what will follow.

Whoever Theuma mentions is likely to be arraigned in court soon afterward.

If Schembri is arraigned, Muscat will come under further pressure to shoulder political responsibility for his best friend’s actions, especially given he has consistently protected him in the past three years. Muscat has already indicated he would consider his own position after arraignments are made though he stressed tonight that only one person is suspected of being the mastermind.

On the other hand, if Fenech is arraigned – and therefore left without a Presidential Pardon – his legal team is likely to mount a formidable legal attack on Muscat, claiming his very involvement breaches Fenech’s right to a fair trial.

They are likely to argue that the Prime Minister should not be involved in the granting of his pardon given that Fenech is offering to expose people so close to Muscat, including his top aide Schembri.

The legal team is also likely to raise the allegations that Schembri tried to influence Fenech’s testimony by offering a pardon and could have therefore done the same in the case of Theuma. This could go straight to the Constitutional Court and eventually the European Courts.

This will put the Prime Minister under fresh pressure to resign so as to avoid facing further criticism for this conflict of interest.

It will also shift the attention on the Prime Minister and his closeness to Schembri, who he hosted at his home in Burmarrad on the eve of Schembri’s arrest.