An Irishman wanted over the brutal stabbing that left a man with a severed ear was allowed into Australia despite being jailed over the death of another victim in 2013.
Officers are searching for Patrick Farrell, 29, after victim Oliver Solan was left in a pool of blood in a corridor in a Randwick apartment block in Sydney's east on August 29.
Patrick Earle, 23, and his girlfriend Katie Aileen Murtagh, 26, have already been charged over the alleged attack.
Police allege Farrell was part of a group involved in the attack on Mr Solan.
He is also wanted over an assault on a man at Matraville in November last year.
The hunt for Farrell comes after he was jailed in Ireland in 2013 for three years over the violent death of 20-year-old Andrew Dolon before he made the move to Australia.
Patrick Farrell, 29, (pictured) is being sought over the attack on Oliver Solan on August 29, as well as a separate one-punch assault in Sydney in November 2019
Neighbours found victim Oliver Solan, 30, barely conscious in a hallway at a Young Street apartment block in Randwick, in Sydney's east, about 8.40pm on August 29
Mr Solan was left with a severed ear and a punctured spleen which later had to be removed.
Earle, Murtagh and Mr Solan had been drinking together at the couple's home on the night of the alleged stabbing.
An argument between the two men ensued, with Mr Solan allegedly the first to attack Earle causing injuries to his arm.
Mr Earle suffered a dislocated arm and cuts to his head before allegedly contacting his friend John Dunlea to ask for help.
At about 8.30pm, Mr Dunlea, along with two other Irishmen, Patrick Farrell and Christopher Morrison, arrived at the apartment complex where Murtagh let them in.
The unit block (pictured) was splattered with blood after the alleged attack
Mr Solan was then allegedly stabbed several times.
CCTV evidence shown to Mullingar Circuit Criminal Court during Farrell's case showed the victim put his hands out and begged 'please don’t hit me'.
The footage showed the convicted killer hit the biomedical student twice, critically injuring him, and he died in hospital soon after.
NSW Police have issued an appeal for Farrell who is wanted over an alleged attack in the beer garden of a hotel in Matraville in November where a 56-year-old was knocked unconscious.
Patrick Earle, 23, and his girlfriend Katie Aileen Murtagh, 26, have both been charged over the alleged brutal attack of a man in a unit in Randwick, in Sydney's eastern suburbs, on August 29
Mr Earle's girlfriend Katie Murtagh, 26, was also charged over the August 29 incident
Footage shows Earle being handcuffed and put into the back of an ambulance