At least one member of Economy Minister Chris Cardona’s secretariat was called in for questioning by police on Sunday evening, sources told Times of Malta.

The individual is a low-level ministry worker from Valletta known to the police as a person of interest in past criminal investigations. He was briefly questioned by investigators working on the case of murdered journalist Daphne Caruana Galizia before exiting police headquarters in Floriana.

Times of Malta could not confirm media reports that two other members of Dr Cardona’s ministry had also been hauled in by investigators. 

Economy Minister Dr Cardona was himself questioned on Saturday and left a short while later. His ministry subsequently issued a statement saying the minister was asked “to provide some clarifications, including on speculations that were made about him in the past”. 

The minister was a frequent target of Ms Caruana Galizia’s and was suing her at the time of her murder, in October 2017. Ms Caruana Galizia had alleged that Dr Cardona and one of his aides had been spotted at a German brothel while abroad on official government business. The case was dropped in the months following her murder. 

Earlier on Sunday, police rearrested businessman Yorgen Fenech and continued their interrogations where they had left off before he was admitted to hospital on Saturday afternoon. 

Mr Fenech was arrested at dawn on Wednesday. 

Investigators are also speaking to suspected middleman Melvin Theuma as they try to piece information together and crack the case. Mr Theuma has been promised immunity from prosecution if information he provides can be corroborated. 

"All persons which were in some way mentioned were interrogated," a source told Times of Malta. 

Despite a flurry of police activity surrounding the case over the past week, investigators have yet to press charges against any person they have questioned in relation to the case.