Prime Minister Joseph Muscat on Thursday refused to say if he was still in touch with his former chief of staff Keith Schembri.
Mr Schembri has disappeared from public view ever since his arrest and subsequent release.
Replying to questions by Times of Malta, Dr Muscat denied having any prior knowledge about the plot to blow up journalist Daphne Caruana Galizia.
Asked if he was confident Mr Schembri was not aware of the plot, the outgoing prime minister said that was up to the police to determine.
Mr Schembri resigned from his role last month hours before being hauled in for police questioning about the murder.
Suspected mastermind Yorgen Fenech has implicated Mr Schembri in the plot to gain immunity from prosecution.
He also said Mr Schembri leaked him key details about the ongoing investigation into the journalist’s death.
Mr Fenech claimed on Thursday that Mr Schembri had told him that his phone was being tapped.
Dr Muscat said on Thursday that Mr Schembri’s name never featured in briefings given to him by investigators.
Mr Schembri sat in on briefings given to the prime minister by the security services.
Dr Muscat said he had his “own opinion” about Mr Schembri’s presence during these briefings but refused to elaborate due to ongoing investigations.
The prime minister reiterated that he had no prior knowledge of the plot and Mr Schembri’s name never featured in briefings.
During shocking testimony on Wednesday, Melvin Theuma, the middleman in the plot, described meetings with various members of Dr Muscat’s staff, including with Mr Schembri, OPM head of customer care Sandro Craus, and a former member of the prime minister’s security detail.
Mr Theuma was given a government job some months prior to the October 2017 bombing.
Times of Malta revealed on Tuesday a letter written by Mr Theuma, claiming both Mr Fenech and Mr Schembri ordered and bankrolled the killing.
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