Charlie Huynh watched a graphic video of police gunning down an armed man at Sydney's Central Station unaware it was his half-brother, who lay dead on the floor.
On Wednesday at 6.45pm officers were called to a flower shop on Eddy Avenue in Haymarket to reports of an armed robbery.
The man, who had threatened a florist with scissors and broke glass outside Sydney Central Station before he was shot has since been identified as Danukul Mokmool.
"A friend of a friend of mine sent to our group a video and it was clear everything was perfect and I sort of saw an Asian character and I thought 'Oh wow, the cops actually shot him'," Mr Huynh told Fairfax Media on Thursday.
It wasn't until police knocked on his door hours later that he found out it was his troubled older sibling.
"It is devastating to hear he has left this life pretty early," Mr Huynh said.
Police reportedly yelled at Mukmool inside to put the scissors down and also tried to use Tasers, but they did not go off and he did not stop.
He is then seen appearing to run at police before he was shot four times before falling to the ground dead.
Mr Mokmool, who was on mental health medication and had done time in prison according to his sibling, was shot dead after a short stand-off with police on Wednesday night.
Central Station florist Manuel Theoharis was at his shop about 6.30pm when 30-year-old Mr Mokmool allegedly grabbed him from behind and threatened him with a bottle.
Pictured: Man shot by police at Central Station identified as Danukul Mokmool
'Police had no choice': Florist defends officers' decision to shoot Sydney man 'armed with scissors'
Shocking moment man armed with scissors is shot by NSW police
Mr Theoharis, 73, says he initially thought his attacker was a friend playfully surprising him until he felt the jagged glass pressed against his neck.
He managed to escape the man's grip before he grabbed a pair of scissors and kicked over buckets of flowers, breaking vases.
Police shot Mr Mokmool after he allegedly refused to put down the scissors.
Mr Theoharis said officers had escorted him around the corner when he heard loud shots.
“I don’t think they had a choice because he could have run out there while he was holding the scissors to hurt other people,” he said.
"I feel sorry for him, he's not alive and I'm happy. I have my life but I could be where he is," he said. "I was in trouble."
Mr Mokmool attended a medical centre at Liverpool each morning and was known to disappear when he had things on his mind, Mr Huynh said, which is how he believes his half-brother came to be in the city.
"He does have (issues with mental health and drugs). Sometimes he'll have a go here and there," Mr Huynh said.
"To be honest ... he was more verbal ... This has shocked my whole family and shocked me."
Cleaning up broken glass and scattered flowers with family and friends on Thursday morning, Mr Theoharis said his attacker didn't ask for money.
"The only thing he said was, 'Call the police, don't move'."
A police critical incident investigation team is examining the shooting and will report to the coroner.
NSW Police are encouraging anyone with information to call Crime Stoppers on 1800 333 000 or by using the Crime Stoppers online reporting page.