Police are hoping this man might shed light on how two little girls died in a hot car on Saturday.
Darcey-Helen, 2, and Chloe-Ann, 1, died inside a black station wagon parked across the front yard of their family home in Logan, south of Brisbane.
Their mother, Kerri-Ann Conley, 27, has been charged with their murders, as well as possession of dangerous drugs and possession of drug utensils.
Police this afternoon issued a statement saying they were appealing for help identifying a potential witness as part of their investigation into the girls' deaths.
"Investigations have shown that a man wearing a high-visibility shirt walked in a southerly direction along Logan Reserve Road, towards Muchow Road, around 1.15pm that day," they said.