No evidence could confirm claims that the son-in-law of a missing World War II veteran killed Leslie Ralph Ball at his north Queensland home, an inquest has heard.
But a detective involved in a 2017 review believes David Phillips had some involvement in his the 73-year-old father-in-law's disappearance.
Mr Ball, a retired builder who served with the Royal Australian Air Force in Darwin, was reported missing in Townsville in May 1993.
Family friend Brian Murphy told the re-opened inquest into Mr Ball's disappearance that Mr Phillips confessed in the 1990s to killing his father-in-law in his garage in retaliation for sexually assaulting a girl.
Detective Senior Sergeant Chris Knight said on Tuesday no forensic evidence was found to back up Mr Murphy's claim during a 2017 review.
However, he believed Mr Phillips - who died in 2015 - was the "most likely suspect"Â based on opportunity and inconsistencies in his statements.
A 1990s inquest closed after the coroner was unable to find Mr Ball's disappearance was due to foul play but reviews were held and witnesses interviewed again.
A 2017 review report containing new findings was submitted to the Coroners Court and the inquest was re-opened at the attorney-general's direction.
"I recommended that David Phillips should be identified (in the 2017 review report). I do believe he had some involvement in Leslie Ball's disappearance," Det Sen Sgt Knight said.
"Whether that was murder or a cover-up, that is my recommendation ... and I maintain that opinion to this day."
He believed Mr Phillips and his wife - Mr Ball's daughter Leanne Phillips - were part of a "constructed lie" after the WWII veteran disappeared.
Ms Phillips on Monday told the inquest that the last time she saw her father was when he visited her in a Brisbane hospital in April 1993.
Mr Ball's car was found abandoned at a train station car park.
However, Det Sen Sgt Knight said a train ticket in Mr Ball's name was a forgery and Queensland Rail confirmed that the veteran did not travel that day.
"That is a sequence of events that I find hard to believe," he said of Mr Ball's hospital visit.
"And David and Leanne have maintained that account for many years.
"That remains to me ... a real sticking point in terms of involvement in or at least knowledge of some of the circumstances around Leslie Ball's disappearance."
Coroner Stephanie Gallagher is considering whether Mr Ball died and the identity of anyone involved in his disappearance or death.