Some media reports have Mr Carino as 19 while others say he was in his early 20s.
Mr Ripley said his brother was a "happy chappie" and was "always smiling".
Sydney newspaper the Daily Telegraph said Mr Carino was found unconscious with head injuries near a 24-hour gym and that police were alerted by an anonymous tip-off from a call at a phone box nearby.
It reported that Mr Carino was believed to be a painter from New Zealand and had a 3-year-old child.
Friends told the Sydney Morning Herald that he grew up around Riverwood and had moved back into the area in the past two months.
One of them said a Maori ceremony was planned to "farewell his spirit".
"We say a prayer, sing a song in our language and the men do a haka," the friend told the Sydney Morning Herald. "It's just a cleansing to send him off."
Mr Ripley's parents reportedly live in Newcastle and he has extended family in New Zealand.
Circumstances leading up to his death are now under investigation.
In the early hours of yesterday morning, around the time Mr Carino was found in the lane, Mr Ripley posted a message on Facebook asking where his brother was.
"Does any one know where Roddy Carino has gone to," the message read.
A man named Rod Carino then commented on the message to say Roddy Carino was at St George Hospital.
Detectives have ruled out a stabbing or shooting. They have indicated a crucial piece of evidence could be in the triple zero [emergency] call made just before 1am from a nearby public phone.
- additional reporting: AAP