VALLETTA, Malta — Soon after a car bomb killed Malta’s best-known journalist, Daphne Caruana Galizia, two years ago, the prime minister’s chief of staff had a hot tip for reporters covering the murder: It was a mafia hit by an Italian fuel-smuggling racket.

More than two years later, Keith Schembri, the official who promoted that bogus story, is now himself under a cloud of suspicion in the murder plot, along with a multimillionaire businessman, Yorgen Fenech, 38, a close friend who was arrested at sea while trying to flee on his yacht.

Slowed down for months by phony leads and obstruction by the government, which tipped off suspects about imminent arrests, the investigation into Ms. Caruana Galizia’s murder suddenly picked up speed late last month after a self-confessed middleman in the murder plot, fearing for his life, started talking.

The inquiry is now closing in on what the murdered journalist’s family and many others see as the real culprit: not Italian Mafiosi but what many here call Malta’s own “mafia state.”