Victorian homicide squad detectives are questioning the two men captured on CCTV moments before a fatal assault on a Melbourne street.
Police say they located one of the men on Saturday afternoon, but they say he is not under arrest.
A second man, aged 27, handed himself into police on Saturday night.
Police say they are both assisting with their inquiries.
It follows what police have described as an unprovoked attack on a 21-year-old Parkville man who was kicked in the head outside a McDonald's on St Kilda Road, Melbourne, just after 1am on Saturday.
The suspects fled the scene. The victim died from his injuries an hour later in hospital.
His name has not been released.
Police say the victim was standing outside the McDonald's when a fight allegedly started involving the two men, who had just bought some food.
"He was grabbed by the arm and violently thrown to the ground head-first, and then kicked to the head," said homicide squad Detective Sergeant Sol Solomon.
"He lapsed into unconsciousness immediately," he told reporters.
Both men involved in the assault fled south along St Kilda Road, Det Serg Solomon said.
The victim was taken by ambulance to the Alfred Hospital with critical injuries.
"It's yet another violent, senseless assault occurring on a public street in Melbourne late at night," Det Serg Solomon said.
Police say the victim was well dressed in a black suit and shirt but not carrying any identification.
There was no indication he knew his attackers.
"There appears to have been a discussion leading up to the assault. We're not aware what words were exchanged," Det Serg Solomon said.
