He tried to dissuade the emperor, who counted him as a close and loyal friend, from going to visit Babylon 5 in 2259, citing the Emperor's failing health as too fragile to risk the trip. The Emperor insisted on going anyway, and shortly after his arrival he suffered a crippling heart attack. Malachi learned of this almost right away, and knew that chaos would follow as there was no clear line of ascension. He was assassinated by men loyal to Lord Refa to make it possible for Refa's faction to put Cartagia on the throne. 
His death was told to everyone but the conspirators to have been a suicide, although several prominent politicians (such as Urza Jaddo) were able to see through the lie. Londo knew nothing of the murder until Jaddo told him.  Londo later told Lord Refa (just before Refa is killed) he had considered Malachi a "dear and trusted friend." 
- Malachi's sole appearance was in ("The Coming of Shadows"), but he was referenced in ("Knives"), ("And the Rock Cried Out, No Hiding Place") and ("The Long Night").
- Malachi was not named during and was credited simply as "Centauri Prime Minister". His name would be mentioned in later episodes (see above), named of course for Malachi Throne.