Cars found during Vic murder investigation

A man wanted for questioning over the murder of his brother at a Melbourne shopping centre is still on the run but police have found two of his cars.

Jonathan Dick's blue Ford sedan was found parked on a back road in Ivanhoe East on Saturday.

It was discovered eight days after his brother, David, was fatally slashed in the head with a long-edged blade as he stepped out of a car park lift at Westfield Doncaster on February 3.

Police want to talk to Mr Dick, 39, who has been missing since February 6, and have urged him to hand himself in.

Officers thought he might have travelled to NSW or Queensland and have been looking for him and his two cars.

Investigators on Monday said one car owned by Mr Dick was "disposed of" prior to the murder. They did not say what that meant.

They want public help finding out how and when the blue Ford sedan came to be on Wamba Road in Ivanhoe East.

Mr Dick was captured on CCTV footage near the scene of his brother's murder on the day of the attack and the previous day.

He was recently diagnosed with a mental health condition and hasn't been taking his medication, police say.

Police still don't know what motivated the attack.