Seven teenagers as young as 14 have been charged with murder and face life sentences after a man was assaulted and his car was stolen.

The teens - including girls aged 14 and 15 - had their charges upgraded after a 27-year-old man died following an alleged attack in Brisbane's inner-north.

A group of teens are accused of assaulting the man and stealing his blue 2025 BYD Shark 6 vehicle at Kelvin Grove about 10.30pm on July 24.

"The group fled in the alleged stolen car prior to police arrival," a Queensland Police statement said.

Emergency services located the man and he was taken to Royal Brisbane and Women's Hospital.

The vehicle was found almost 20km away at Holland Park the following morning.

The man was declared deceased almost two weeks later on August 6.

A total of nine children - six boys and three girls - were initially charged with a number of offences over the alleged attack.

On Thursday, a week after the man's death, seven teens - five boys aged from 15 to 17 and the 14 and 15-year-old girls - were each charged with an additional count of murder.

The number of children charged with murder is set to almost triple in Queensland when they appear in Brisbane Childrens Court, expected to be on Friday.

They face life sentences under the Liberal National government's controversial "adult crime, adult time" laws introduced after it won the 2024 state election.

It boosts the number of juveniles charged with murder under the new laws from four to 11, spanning four cases.

It also marks the first two female juveniles to be charged with murder under the controversial legislation.

Police are appealing for July 24 dashcam and CCTV footage captured on Kelvin Grove's Victoria Park Rd between 9.30pm and 10.30pm and Holland Park West's Barter Ave between 11.30pm and 11.50pm as part of the murder investigation.

They are also seeking witnesses and footage between 8.10pm and 8.40pm on Kelvin Grove Rd near the Musk Ave intersection in Kelvin Grove.

Two potential witnesses have been asked to come forward after they were seen driving in the area.

"Neither driver is believed to have been involved in the alleged offence," police said.

The first potential witness was last seen driving a dark-coloured SUV along Victoria Park Rd, Blamey St and Musk Ave about 10.16pm.

The second was last seen driving a blue sedan at 10.16pm on Carroway St at the Victoria Park Rd intersection.