Former Prime Minister Joseph Muscat's iPhone was wiped clean three weeks before police raided his home and seized it, a court heard on Wednesday.

Muscat also used Google to twice search for information on how to erase iPhone data and how to delete backups of WhatsApp chats, court expert Keith Cutajar told the court.

Cutajar presented a report into Muscat's devices as part of a criminal case against the former Prime Minister.

Cutajar was testifying in the criminal case against Muscat, and others, over the hospitals concession. Cutajar was appointed to crack Muscat's phone after the latter refused to hand investigators the device's passcode. 

Information from the device showed that Muscat's phone was reset on 28 December, 2021, three weeks before his home was searched on 19 January, 2022.

At the time Muscat had refused to give investigators his phone password and in November a court heard that it would take almost a year to unlock the device.

Using specialised software, the court expert tried all possible password combinations to unlock the phone.

The software finally obtained access, but when the court expert tried to examine the phone's contents, he found out that it had been wiped clean.

Keith Cutajar testified that 35gb of the data wiped was retrieved. Data mining and recovery software was then used to retrieve other relevant deleted information.

Lawyer Vincent Galea, who is representing Muscat, requested private messages extracted from Muscat's phone which are irrelevant to the case, be excluded. He also requested the court to appoint an expert in order to identify which data is relevant to the case.

He argued that since some of the extracted messages were sent while Muscat was still Prime Minister, any content relating to his official role and security matters should be excluded.

Galea compared the irrelevant data being considered to a witness testifying on irrelevant matters, and emphasised that irrelevant data should be singled out and not included in the acts of the proceedings.

The prosecution said that the defence is just trying to override the reality that the data was wiped.

Defence lawyers Franco Debono and Stefano Filletti, who are representing another accused in the case, argued the request to extract only the relevant information as evidence should have come from the prosecution itself. 

Lawyer Vincent Galea agreed with Debono and stated it is the prosecution's job to come prepared and bring forward the relevant information.

Debono emphasised that the prosecution should come to court prepared with concrete, relevant evidence and not go on a "fishing expedition".

Ultimately, the court decided to issue a decree in camera, denying both parties access to the USB containing the extracted mobile phone data until a final decision is reached.

At the end of the sitting, the defence lawyers once again raised the point on the rogatory procedure on getting court expert Jeremy Harbinson to testify.

Lawyers Charles Mercieca and Franco Debono said that the rogatory procedure should be the last step, and that other procedures are available.

The prosecution has already submitted the application for the rogatory procedure as a method to get court appointed expert Harbinson to testify, but the defence still needs to reply on the matter.

The sitting was adjourned to 7 May.

The prosecution is led by Inspector Wayne Rodney Borg together with AG lawyers Francesco Refalo, Rebecca Spiteri u Shelby Aquilina.

Joseph Muscat is being represented by Vince Galea, Luke Dalli, Charlon Gouder, Ishmael Psaila u Etienne Borg Ferranti.