They have spoken to dozens of people and are looking for more witnesses.
Police spokesman Andrew McAlley also said investigators had been tracking down newspaper and milk delivery drivers, as well as any other early morning workers, such as bakers, who may have been in the vicinity during the early hours of the morning, to gauge what was going on in the town.
He said they were often the town's "eyes and ears" at that time of night.
"If you are a service provider that hasn't been contacted by police but was in the area at that time, we encourage you to come forward," Mr McAlley said.
Mr Whitehead said forensic evidence and statements from people in the town could be the key to catching the killer.
Mr Voudouris was a popular Paeroa identity, and was farewelled by about 1000 people at a large memorial service held in the town last week.
Following the memorial, Mr Voudouris' brother-in-law, Mike Burke, also appealed for any witnesses to come forward, for the sake of the victim's three grieving children.