She had heard someone had been convicted but was surprised to read last week that it was Hall, an asthmatic Pakeha, as he was not like the person she saw.
"There was no way that guy [Hall] was the build of the guy that I saw. And I believe the guy I saw had come out of the walkway leading to the Eastons' home."
She told police in a squad car who stopped her a little further along the road moments after she passed the suspicious man and also a police officer who interviewed her the next day.
"I had expected to hear from police again or be called to give evidence."
Mr Easton, 52, died in his Papakura home on October 13, 1985 after being stabbed by an intruder with a bayonet as he and his two sons fought him. The identity of the intruder was the central issue of the case.
A key witness, Ronald Turner, identified as "Maori" a man he saw running near where a police dog tracked the suspected offender.
But the statement presented in court was changed, omitting all references to a Maori or "dark skinned" person.
Police also withheld sighting by two other motorists who described Maori or dark-skinned males running from the direction of the crime scene.
Hall volunteered to police that he owned the bayonet but said it was stolen from his sleepout at his family's home.
The New Zealand Innocence Project, which expects to soon file a royal prerogative of mercy petition claiming Hall's conviction is unsafe, will interview Mrs Richardson.
"Her statement to the New Zealand Herald corroborates information from other witnesses' statements," project manager Matthew Gerrie said.
Hall family spokesman Geoff Hall said Mrs Richardson's statement was "an important piece of the puzzle which further highlights the terrible injustice brought upon Alan.
"I am shocked that the Papakura police have even more job sheets and statements from eyewitnesses when we requested these 25 years ago. What more information is there?"
Hall's lawyer Gary Gotlieb was critical of the response from authorities of efforts to have the case addressed, including a decision denying Hall legal aid.
Police had set out "to get Hall who didn't fit one iota" the descriptions of eyewitnesses, Mr Gotlieb said. "It was back in the days before the disclosure regime really started ...
"The law changed quite dramatically and disclosure became far more helpful to the defence."
The trial judge told the jury that Mr Turner's evidence was important but did not know it had been altered.
Mr Turner was not called to give evidence in person and says in an affidavit that he was unaware of the omissions until uncovered by the defence years later.
* New witness backs claim police got wrong man Read Phil Taylor's original story "The missing evidence" online at http://tiny.cc/obhwt