Police are asking anybody who has seen the two orange-coloured bicycles or seen people riding the bikes between 6pm last Saturday and midday Sunday in the Avenues area or near the Whangarei Bowling Club to contact them.
Officers continue to examine the Second Ave house in what they describe as a "very complex" case and expected to be there until today. "The Whangarei community have supplied crucial information allowing the investigation team to progress this matter," Mr Burke said.
An appeal by police to neighbours to check their backyards for items has turned up some items of interest but police would not say if the weapon used to assault Mr Griffin was among them. "We are still seeking items people may have found discarded in the vicinity," Mr Burke said.
Anyone who can help police with their investigation should contact officers on 09 430 4500 or Crimestoppers anonymously on 0800 555 111.