Mahmoud Hrouk's alleged killer spends second night behind bars

The man accused of the sexual assault and murder of Sydney teenager Mahmoud Hrouk has spent a second night behind bars after his case was heard in court.

Police will allege Ayman Terkmani, 22, ate alongside 16-year-old Mahmoud at Villawood McDonald's, in the city's southwest, on a Saturday night two months ago.

That night or in the early hours of May 17, it is alleged Terkmani sexually assaulted the teenager, bashed him and left his bloodied and half-naked body in a vacant house in Fairfield East - only a short walk from the Hrouk family home.

Senior investigators said as recently as Wednesday that they were baffled as to why anyone would want to hurt Mahmoud, a "model" teenager who worked for an uncle during the week and spent his weekends watching footy games with his mother.

Terkmani did not emerge from the cells when his matter was mentioned at Fairfield Local Court yesterday and did not apply for bail, which was formally refused.

Supporters of Terkmani clashed violently with media outside the court hearing. 

His lawyer Fadi Abbas told the court the high-profile nature of the case and the charges meant Terkmani could be at risk in custody.

"If the other inmates know who he is, his life may be in danger," Mr Abbas said.

He told reporters outside court that his client would fight the charges and intended to apply for bail soon.