They are asking this person to come forward to see if they have information to assist the investigation.
Detective Senior Sergeant Matt Cranshaw, Taupo area investigations manager, said police were not suggesting this person was involved in Joseph's death.
"The fact that they were in Tirau at the critical time may mean they can provide information that is useful to this inquiry."
Cranshaw said neighbours in the area were alerted by activity.
"A series of thumps were heard coming from Roma's house. One person was seen walking along Little St away from the address, another was seen up by the front door."
Shortly afterwards a silver four door sedan was seen reversing out of the driveway before driving off towards Bear St.
The family are seeking answers into Joseph's callous and senseless death.
"Roma was a tiny woman in her late 50s. She was violently killed in her own home in the early hours of the morning. Those responsible for this cowardly and brutal murder need to be held to account," Cranshaw said.
"It's really important that people come forward with any information they have whatsoever on the silver sedan or the people seen at and near Roma's place or on State Highway 1 on the morning of 1 May.
"We urge those people with information about this shocking death to do the right thing and tell us what they know."
People can watch the Police Ten 7 segment again on the Police Ten 7 Facebook page.
Anyone with information should contact the investigation team direct on 0800 766 211.
