Ms Dawson vanished following the painful disintegration of her marriage to her husband, whose extra-marital affair with a teenage student grew in intensity throughout 1981.
Lyn Dawson disappeared without a trace 36 years ago.
Days after her disappearance her husband Chris moved his schoolgirl lover into the family home.
Two coroners found Lyn was probably murdered by Mr Dawson in 1982, but he continued to deny his involvement, saying she had run off to join a "religious cult".
While appearing at Southport Magistrates Court on Wednesday afternoon, he sat quietly looking at the floor, trembling at times with his shirt visibly shaking as he breathed.
Details of the police case against Mr Dawson were revealed in court.
He had his head in his hands as the magistrate read out the police case, including allegations of domestic violence against his wife.
The 70-year-old was arrested by detectives on Wednesday morning at his Queensland home.
Mr Cowdery told the ABC's Australian Story the case against Mr Dawson was "weak" without a body.
It has not been determined whether they will fly out of the Brisbane or Gold Coast airport.
"Without a body, without knowing first of all whether in fact she is dead, without knowing secondly if she is dead, how she died, it's very hard to mount a case of a reasonable prospect of conviction just on motive and the undefined existence of means and opportunity".
"Today is an important step forward in that".
In a statement, the Dawson family said it was disappointed.
"We have to also ensure Chris gets due process".
In April NSW Police asked the Director of Public Prosecutions if there was enough evidence to charge Dawson.
"They were predominately statements from witnesses that helped us tie pieces of the puzzle together", he explained.
In a statement, the police said: "In 2015, detectives from the Homicide Squad's Unsolved Homicide Unit established Strike Force Scriven to re-investigate the circumstances surrounding her disappearance and suspected murder".
"We have solved homicides before without identifying the body", Comm.
Police have been criticised for not investigating the disappearance properly.
An application for a warrant was lodged after NSW Police received advice back from the DPP earlier this week.
Detective Superintendent Scott Cook said Mr Dawson is not expected to be questioned by police today.
Cook said the two additional witnesses interviewed as a result of the podcast were "not crucial, but they are corroborative".