Robert Crawford, 49, has pleaded not guilty to murdering his wife Frances at their Upper Lockyer property near Toowoomba on 29 July 2024.
Crawford, dubbed a "love rat" by the prosecutor, is accused of strangling Mrs Crawford then placing her body next to the lawnmower at the bottom of a retaining wall.
The jury was shown graphic images of Frances Crawford's body next to the mower on Tuesday.
Senior Constable Matthew Fender, who took photographs of the scene, admitted that no fingerprints were taken from the mower's steering wheel.
"I don't believe I was told that there was concern that it was staged," he said under cross-examination by Robert Crawford's barrister Saul Holt KC.
Robert Crawford claims that his wife had attempted to move the mower inside herself after she told him to bring it inside before a sprinkler system was activated.
Frances Crawford's children Jessie and Jake have testified that they never saw their mother use the mower.
The mower had been put in reverse and the throttle was halfway open.
Sen Const Fender's photographs showed severe bruising and abrasions to her neck area and a deep gash on the back of her head.
They also showed bloodstains between the steering wheel and body of the mower, as well as a trail leading to Mrs Crawford's head.
Sen Const Fender said he and a colleague also searched in vain for a torn piece of fingernail from the middle finger of Mrs Crawford's right hand.
He agreed with Mr Holt that it was "like looking for a needle in a haystack".
Forensic scientist Owen Esaias, who examined the scene two days after Mrs Crawford's death, also found bloodstains on the rock wall.
He said either Frances Crawford had sustained a head injury in that location, or that the injury was pre-existing.
"I put equal weight on those two scenarios, both plausible," he told the jury.
"I couldn't ascribe any more weight to one over the other."
The jury was also shown bloodstains on a towel from the Crawfords' bathroom.
The jury has heard that Robert Crawford was asked by police if he wanted to take a shower, late in the morning after attempting to resuscitate his bloodied wife.
The trial continues before Justice Lincoln Crowley.
22°C