Lisa Pascoe, 28, an administration worker from London had been staying in a flat near where the killing took place with her partner at the weekend.
She has told police she spotted the two suspects after returning from a night out after midnight on Saturday.
“We got out of the taxi and I thought ‘oh this is a bit rough’,” she said today.
“There was a bit of aggression from two Asian boys and we decided to give them a wide berth. They were making a bit of noise, shouting and acting aggressively.
“It’s scary to think that we could have been there just two or three minutes before it might have happened. We never saw the victim at that point and it’s really frustrating to think that we might have been able to change what happened if we were just a few minutes later.
“The next day when I saw all the police, I thought it was one of the Asian boys that had been murdered, but then we found out it was another man.”
Local shopkeeper Mohammed Jamil, 53, was among many local people in Glasgow paying tribute to William who was known to help many people in the community.
He said: “William was a very nice man, he came into my shop every day to buy something and he was always very friendly.”
Police are not commenting on a possible motive for the attack which took place close to where a teenage white boy was abducted and murdered by a Pakistani gang in a race crime killing in 2004.
Det Chief Inspector David Gailey said: “Mr McKeeney suffered massive injuries to his head and body in what can only be described as a brutal and sustained attack.
“To speculate on a motive at this time is completely unhelpful, and indeed may hinder our investigation, however, we are keeping an open mind as to why it happened.”
He said Mr McKeeney, from Malin Head and his partner, Annemarie Newlands were well known in the area.
”William, who worked locally as a labourer, was a popular man who was ready to help anyone he could,” he added.
It may be two weeks before William’s remains are released for burial in his native Donegal.