Arrest warrants have been issued for Codye Thomson, 29, and his 32-year-old sibling Kaine Thomson-Gleeson after the December 22 incident north of Brisbane.
Chloe Jade Mason, 23, was found dead on Caboolture's Railway Parade in the early hours of December 22.
The brothers were interviewed by police that day but released without charge pending further investigation, Detective Inspector David Harbison said.
"At that early stage of the investigation there was simply insufficient evidence available to indicate their involvement with this homicide," he told reporters on Friday.
The brothers fled interstate and may be camping in northern NSW, travelling in a white Holden Commodore wagon with Queensland registration 953 HO4, police say.
Images of the vehicle were released on Friday by police who confirmed arrest warrants had been issued for the brothers for the offence of murder.
The brothers fled interstate in a white Holden Commodore wagon with Queensland registration. (HANDOUT/QUEENSLAND POLICE)
The car was last sighted travelling through northern NSW on the evening of December 30.
Police said they had issued arrest warrants after receiving further information and were satisfied they had sufficient evidence to bring the brothers before court.
An investigation established Ms Mason knew the brothers and had attended a Railway Parade address where an altercation occurred, police said.
"It is alleged the deceased received a gunshot wound during that altercation and the deceased subsequently died," Det Insp Harbison said.
A rifle was recovered from a Railway Parade crime scene but tests are yet to determine whether it was the murder weapon.
Det Insp Harbison said.Queensland Police were working with NSW police to track down the brothers.
The public have been warned not to approach the pair, who are considered dangerous.
"I would urge these wanted persons to hand themselves in to the nearest police station otherwise police will continue to hunt you - you will be found and arrested on our terms," Det Insp Harbison said.
"They know they are wanted for the murder of Chloe so we fear they will go to lengths to avoid apprehension."
Anyone with information should contact police.
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