The family of murdered Maltese journalist Daphne Caruana Galizia who was killed in a car bomb last month has taken legal action against the police, alleging the investigation is neither impartial nor independent.

Caruana Galizia had done considerable work on exposing corruption in Malta and more recently uncovering the failings of the country’s anti-money laundering outfit, the Financial Intelligence Analysis Unit (FIAU).

Through her work on the Panama Papers leaks, Caruana Galizia was the first to break the news of the involvement of prominent Maltese politicians in the exploitation of offshore tax regimes.

Her family is now suing Malta’s chief of police because the investigation is being presided over by Malta’s deputy commissioner Silvio Valletta, whose wife, Justyne Caruana (no relation to the journalist), is a senior member of the government.

Ms Caruana was recently promoted to become the minister for Gozo, by Maltese Prime Minister Joseph Muscat.

Caruana Galizia had been a vocal critic of Mr Muscat, Mr Valletta and his wife.

Caruana Galizia’s family has claimed the numerous connections in the murder investigation could breach their right to a fair hearing.

“The involvement of the deputy commissioner Silvio Valletta violates the independence and impartiality of any investigation into the loss of life,” the journalist’s family say in their court filing.

According to the Malta Independent, the deputy commissioner and his wife had both been the targets of “harsh criticism” by Caruana Galizia.

In particular, Caruana Galizia had criticised the shortcomings of the FIAU Board after the publication of the Panama Papers. Deputy Commissioner Valletta is himself an FIAU member, a fact which Caruana Galizia had highlighted in May 2017.

Caruana Galizia’s most explosive investigations centred around the Panama Papers leaks, from law firm Mossack Fonseca.

The leaks apparently linked Mr Muscat and other senior members of the Maltese government to offshore companies.

She also wrote about a web of transactions between individuals in the top tiers of the Maltese government and Azerbaijan, which has a key gas contract with Malta.

In particular, she alleged that the prime minister’s wife was the named owner of the offshore company Egrant and said payments from the daughter of the President of Azerbaijan had been sent through Egrant, The Guardian reports.

Mr Muscat described the allegations as “fabricated”, and has pointed out that no documents proving the link had been published.

At the time of Caruana Galizia’s death he had been in the process of suing her for libel over the claims.

In the recent court filing, the journalist’s family said there could be no objective analysis of evidence unless the persons involved in the investigation are “completely independent from any connection which could cast a shadow” over their objectivity and impartiality.

The Maltese government has offered a 1m euro reward for information about the journalist’s murder.