Cardboard cut-outs of ministers Konrad Mizzi Chris Cardona and chief of staff Keith Schembri were placed at the foot of the Office of the Prime Minister to mark the eight months since the assassination of Daphne Caruana Galizia.
Dr Mizzi and Mr Schembri are depicted in handcuffs and wearing orange jumpsuits while a naked cut-out of Dr Cardona depicts him holding a sign saying: "What's inside the envelope?"
The three men featured prominently in the Daphne Project, an international journalistic collaboration seeking to continue the stories reported by Ms Caruana Galizia.
The stunt was organised by the anti-corruption group Il-Kenniesa.
Streamers were also put up in various localities bearing the words: "We will not be silence. 8 months on". Photos sent to Times of Malta also show similar messages placed outside the Maltese embassy in Athens.
A vigil is expected to be held at the foot of the makeshift memorial in Valletta on Saturday.
Activists have held an activity on the 16th of every month to mark the date when the journalist and blogger was killed in a car bomb.
Three men stand charged with carrying out the murder but the mastermind has not yet been identified.