Police want the person allegedly responsible for stabbing a 16-year-old boy to death in Brisbane's CBD to hand themselves in.
The victim and offender are believed to have known each other and were seen talking in the lead-up to the stabbing near Roma Street train station at about 8pm on Thursday.
"Talk to your family, but it's time for you to come forward to the police and give your side of the story," Detective Superintendent Tony Fleming said on Friday.
A passer-by called emergency services after the boy walked to nearby Suncorp Plaza and collapsed. He was rushed to the Royal Brisbane and Women's Hospital where he died.
It's believed the victim and offender were talking in Queen Street Mall shortly before the stabbing.
"There was no evidence to indicate any violence or tension at that time," Det Supt Fleming said.
He said a group moved from the mall to Emma Miller Place where the pair appeared to have another innocuous conversation before the victim was stabbed in the stomach.
The investigation hasn't revealed gang involvement, but Det Supt Fleming called for calm if there were tensions simmering.
"Our primary focus here is on a homicide investigation but if there's going to be ongoing tension, that's a key area of focus for us.
"We don't want this to get worse. If people are unhappy, retaliatory actions (are) not going to benefit anyone."
The alleged offender is believed to be either in his teens or early 20s.