The authorities in Malta arrested a prominent businessman on Wednesday in connection with the killing of the country’s best-known investigative journalist, Daphne Caruana Galizia, who had accused companies and politicians tied to him of corruption.

The businessman, Yorgen Fenech, was detained on his yacht just after it left port, as he tried to leave the country, local news outlets reported. The arrest is the biggest development in almost two years since the killing of Ms. Caruana Galizia, a case that had appeared to be stalled. Her family and friends have said that the government has no interest in solving it.

The police declined to comment about the arrest, but Prime Minister Joseph Muscat confirmed to reporters that Mr. Fenech had been detained in connection with the murder case.

The announcement came a day after another man suspected of being a go-between in the killing was arrested, but it was not clear how, or whether, the two arrests were linked. Mr. Muscat had offered clemency to the man arrested on Tuesday — his name was not released — if he would identify the person who had ordered the killing.