The man twice wrongfully convicted of the infamous 1970 Crewe murders has stood trial for the past eight days, charged with four counts of indecent assault and one count of rape.
But since the jury at Manukau District Court retired around midday on Thursday, it has not reached a unanimous decision and has been discharged.
Thomas showed no emotion while he stood in the dock. The matter will be addressed again at a hearing in August.
Judge John Bergseng directed the group of the option of a majority verdict, in which one juror can disagree with 11.
"I'm asking you to retire again, see whether you can reach a verdict," he said after it indicated it was hung on Monday morning.
But after the jury also failed to reach a majority verdict , Thomas, 83, will have to sit another trial in relation to the allegations of historical sexual offending.
He was twice found guilty of the infamous murders of Harvey and Jeanette Crewe, who were shot in their Pukekawa farm house in 1970 and dumped in the Waikato River.
Thomas stood trial in 1971 and 1973 and was jailed for nine years before being pardoned and awarded $950,000 in compensation after a Royal Commission of Inquiry found detectives had planted evidence in the case.
Thomas never received a formal apology and the case has never been solved.
Two complainants came forward to police in 2019 with allegations of historical sex offending. They have automatic name suppression.
They had been triggered to finally report the allegations after seeing a petition calling for Thomas to receive a formal apology from police over the Crewe murders, they said.
Throughout an eight-day trial the court heard sensitive and intimate evidence from the two complainants.
Thomas was accused of inappropriately touching one woman on multiple occasions and forcing her to touch him.
It drove her to drink, the jury heard.
"I got through it by just sort of binge drinking. Every three weeks I'd hit the bottle," she said.
"I didn't want any money from Arthur Thomas, I wanted an apology."
She claimed Thomas wrote a letter to her saying he could not "take responsibility" for the alleged offending.
Thomas was accused of coercing another woman into performing sexual acts with a man while Thomas watched.
He told them to "get on the bed" and they both remember having to remove some clothing.
The man involved said the memories have haunted him and he tried to block them out.
"It still sticks in my mind and still upsets me … I do not know why I did it."
In a police interview played to the jury the man said he would like to apologise.
Thomas was also accused of raping the woman.
All the two complainants wanted was an apology, they said.
A meaningful apology, Crown prosecutor Aaron Perkins QC said.
An apology Thomas did not give them.
The Crown attempted to separate the historical sex offending trial to Thomas' two trials for the Crewe murders, calling them "chalk and cheese".
"Being responsible for what he did to them, the sexual offences, is an entirely different thing to innocence on murder charges," Perkins QC said.
"They have disclosed to a room full of strangers intensively private information and details ... do you really think they are making that up?" he said.
But defence counsel claimed the allegations were all lies - a "fantasy land" - motivated by resentment and deep-seated anger within the complainants for not receiving some of Thomas' compensation.
"This is where they have ended up, to destroy Arthur Allan Thomas with false allegations," Marie Dyhrberg QC said.
In Judge Bergseng's summing up, he acknowledged there were inconsistencies in the people who gave evidence,
"Their memory may have faded or unconsciously altered to the point where their recollections are unreliable," he said.
"I'm not being critical of their evidence. These are events from a long time ago and at times it was difficult for them to remember."
Much of the details around the allegations, such as time and place, remain heavily suppressed to protect the identity of the complainants.
What is a hung jury?
A hung jury is when the jury can't reach a unanimous verdict or a majority verdict following the trial.
The jury is discharged and it may lead to a new trial for the defendant with a new panel of jurors.
If the jury can't reach a unanimous verdict after a reasonable time, the judge may accept a majority verdict. In criminal cases, this means one juror can disagree with 11 other jurors.
