Vic man charged with attempted murder

A Victorian man has been charged with attempted murder over a roadside assault that left a good Samaritan with brain damage.

The victim, a 51-year-old Warburton man, was bashed repeatedly with a cylindrical object witnesses have described as a pole after he stopped to help a woman he knew whose car had broken down.

A 28-year-old Wantirna man will appear in the Melbourne Magistrates Court on Wednesday charged with attempted murder and armed robbery.

Detective Sergeant Mark Smithwick of Yarra Ranges criminal investigation unit said the victim was taken to hospital in a critical condition after the February assault and has suffered permanent brain injuries.

"He will never be all right. He has suffered permanent injuries. He will never be the same," he told AAP.

Police on Wednesday conducted pre-dawn raids on five addresses in Wantirna, Bayswater, Ferntree Gully, Rowville and The Patch, all in Melbourne's outer-east, arresting five people.

Police seized cash, a number of pills and powder believed to be methamphetamine.

Another man, 31, of Menzies Creek, was charged on Tuesday with armed robbery, intentionally causing serious injury and other assault-related offences over the February 4 attack at Yellingbo, east of Melbourne.

He has been bailed to appear in the same court for a filing hearing next Tuesday.

Four other people - a 53-year-old man from The Patch, a 25-year-old Wantirna woman and two 21-year-old men - are assisting police.

A 37-year-old Warburton woman interviewed by police earlier this month is expected to be charged on summons with offences related to the assault.