Homicide squad detectives have upgraded one of the charges relating to the Flinders Street incident to murder.
Police issued a statement on Tuesday, following the news of the death of an 83-year-old man on December 29.
The additional charge was filed this afternoon.
The 32-year-old Heidelberg West man, Saeed Noori, had previously been charged with 18 counts of attempted murder and one count of conduct endangering life.
He will appear again at Melbourne Magistrate's Court on May 30.
Three people are still in hospital following the incident.