One man in his late 20s who was arrested after being identified through shop security footage is scheduled to appear in court this morning charged in connection with the incident.
But investigating officers are appealing to shoppers and other pedestrians who saw what happened or witnessed any of the altercation that preceded it to come forward to help them clarify the sequence of events.
The dead man, named as 28-year-old Eoghan Dudley from Newcastle, carried no official identification, and was identified by acquaintances over the weekend with the help of his numerous dragon tattoos.
He was also homeless and his name was withheld until all family members had been tracked down and informed of the tragedy which happened in front of horrified onlookers.
He died instantly when he fell under the wheels of a 145 double-decker bus at the busy Dawson St/Nassau St junction just before 4pm on Thursday afternoon when the area was packed with shoppers, office workers and students from nearby Trinity College.
It is believed there was an altercation involving a number of people moments prior to the accident and the deceased was pushed or punched before stumbling out on to the road.
The scene was sealed off for 24 hours as a forensics team scoured the area and CCTV footage from surrounding shops and offices was gathered but gardaí say the help of the public could still prove crucial to understanding exactly what happened.
One other man who was at the scene was interviewed by gardaí but was not arrested but other arrests are expected to follow. A separate Dublin Bus investigation is under way although witnesses said there was nothing the deeply shocked driver could have done to prevent the accident.
* Anyone who can help with the investigation can contact Pearse St Garda Station on 01 6669000, the Garda Confidential Telephone Line 1800 666 111, or any Garda station.