Grave fears held for missing millionaire

Homicide police have admitted for the first time they hold grave fears for missing Melbourne businessman Herman Rockefeller, as they question two people over his disappearance.
• Family 'struggling' as search fails to locate missing millionaire

Homicide and crime investigation police raided a house in South Street, Hadfield on Thursday and took a 57-year-old man and 41-year-old woman into custody.

No charges have been laid.

Forensic teams combed the property and on Friday morning three uniformed officers were guarding the scene.

Victoria Police Leading Senior Constable Kendra Jackson said detectives had worked through the night and were yet to establish a motive for Mr Rockefeller's disappearance.

"Homicide squad detectives confirm they hold grave fears for Mr Rockefeller's welfare and investigations are continuing," she said in a statement.

Police had previously said they were keeping "an open mind" in their investigation.

Mr Rockefeller went missing soon after arriving at Melbourne Airport from an interstate business trip on the night of Thursday, January 21.

He has not officially been sighted since, although police are investigating several reported sightings including one at a general store at Gordon, about 10km from where Mr Rockefeller's abandoned car was found.

The Hadfield home was raided about 4.30pm (6.30pm NZT) on Thursday.

On Friday morning, shutters were drawn at the modern brick townhouse which was cordoned off by police tape.

Three uniformed officers stood in front of the property guarding the scene.

The townhouse, which is one of a block of six, is located about 15 minutes' drive from Melbourne Airport.

The garage door at the property is open but reveals no clues to the mystery. A lawn mower, bike and gardening tools are visible inside.

A mushroom coloured station wagon with a `for sale' sign on it is parked on the front lawn.