A biomechanics expert has told a jury it seemed very unlikely a mower could end up directly on top of Frances Crawford, whose husband is accused of killing her; the defence says her death was a tragic accident. Professor David Ackland said simulations could not get her body to 1.8 metres from a retaining wall, though he said that distance was possible if the mower was moving forward at maximum speed with no impact to her head on the wall. He also said Frances could not have been seated on the mower when her head struck a rock. The evidence came as the trial of her husband, former RAAF pilot Robert Crawford, heard further admissions about his affairs and his statement that he was enjoying being single during the couple's separation.
Crawford, 49, has pleaded not guilty to murdering his wife at their property in rural south-east Queensland in July 2024. The defence has told the jury her death was a tragic accident, and that Crawford believed she died while moving a ride-on mower because the sprinklers were going to come on.
On Wednesday, Crown prosecutor Chris Cook asked Ackland whether it was possible for Frances to have hit her head on a rock, where blood was found, and be found 1.8 metres from the retaining wall. Ackland answered: "In my opinion, no." He said simulations were unable to get her body to that distance, and that "to get the body past 1.8 metres, we actually need to have a projectile motion without any impact to the rock, almost like being thrown off with that velocity." He told the jury his modelling showed Frances could not have been on the mower at the time her head struck the rock, given the distance between the bloodstained rock and scratch marks from the mower at the top of the wall. Ackland stressed that his focus was on the body's final resting place, but it seemed "very unlikely" that the mower could end up directly on top of Frances at the bottom of the wall.
The trial has previously heard that Crawford had a string of extramarital affairs dating back more than a decade, including with three RAAF colleagues, and that the prosecution alleges he killed Frances to avoid a costly divorce. Her death came days after the couple's last session with a psychotherapist, who told the court Frances was working on an "exit plan" to leave the marriage.
In admissions read to the court on Wednesday, details of Crawford's relationships were made public. He had a relationship with buyer's agent Rebecca Lawler in the months after his separation from Frances in mid-2023. The jury heard the pair exchanged 9,979 messages and photos between October and November 2023. In early October, during a dinner at the Sherwood property in Brisbane's south, Crawford told Lawler he and his wife were exploring divorce. According to the admissions, he blamed Frances for his inability to attend church and said he did not know if the marriage was salvageable. He also said he was enjoying being single. Crawford told Lawler the Upper Lockyer property meant a lot to him and that he was annoyed he had to move out while Frances got to stay.
The court heard from Frances' solicitor, Meagan Murrell, who said Frances had contacted her in July 2023 about possible divorce settlement issues. In messages shown to the jury, Frances wrote that Crawford had withdrawn $6,000 from their funds, leaving her with $150, and on July 22 she wrote: “Can you please go ahead with financial separation. I need to get out of this relationship.”
On Tuesday, the jury was read Crawford's police statement in which he detailed the night of Frances' death. He said the couple had dinner, read the Bible together, played games and later were “snuggling on the couch sharing a heated blanket”. He told police he last saw her alive about 9.45pm and later found her pinned under the mower; the court heard he called Triple Zero at 3.37am.
The trial before Justice Lincoln Crowley continues.
Analysis
Why This Matters
- The expert testimony directly challenges the defence's contention that Frances Crawford's death was a tragic accident, providing the jury with biomechanical evidence that the prosecution says supports a murder scenario.
- The details of Crawford's relationships and his expressed enjoyment of being single during separation bolster the prosecution's case that he had motive and was not committed to the marriage.
- The trial has drawn significant public attention in Queensland and highlights the use of forensic biomechanics in murder cases involving staged accidents.
Background
- Frances Crawford died in July 2024 at the couple's Upper Lockyer property west of Brisbane. Her husband, former RAAF pilot Robert Crawford, was charged with her murder, with the prosecution alleging he staged her death to look like a lawnmower accident to avoid losing millions in a divorce.
- Crawford has pleaded not guilty, maintaining that her death was a tragic accident. The defence has pointed to the couple's routine on the night as evidence of a normal relationship.
- The trial has been running since early November 2026, with evidence from psychotherapists, police crash investigators, and the accused's own police statement.
Key Perspectives
Prosecution: Argues Crawford murdered his wife to avoid a costly divorce, citing his history of extramarital affairs, financial deception, and Frances' efforts to leave the marriage. The biomechanics expert's testimony is presented as evidence the death could not have been an accident.
Defence: Maintains Frances died accidentally while moving the mower to avoid sprinklers, and has emphasised Crawford's detailed account of the evening and his immediate attempts to free her. Defence barrister Saul Holt KC has challenged the expert's conclusions in cross-examination.
What to Watch
- The jury's assessment of the biomechanical evidence and how it interacts with the extensive relationship and motive evidence presented by the prosecution.
- Further cross-examination of prosecution witnesses by the defence, particularly any alternative explanations for the body's position.
- The judge's summing up and the jury's eventual verdict in what has become a closely watched trial.
Checked
7 claims in this story checked against 2 sources: 6 supported.
Show each claim
- SupportedThe expert said it seemed very unlikely the mower could end up directly on Frances.Sydney Morning Herald - Latest News: “it seemed “very unlikely” to him that the mower could “end up directly on top” of Frances at the bottom of the retaining wall.”
- Partly supportedThe jury heard Crawford exchanged nearly 10,000 messages with another woman.Sydney Morning Herald - Latest News: “The jury heard the pair exchanged 9979 messages and photos between October and November 2023.”
- SupportedThe jury heard Crawford said he was “enjoyed being single” during the separation.The Age - Latest News: “Husband accused of staging mower death ‘enjoyed being single’ during separation.”
- SupportedAckland said simulations could not place Frances 1.8 metres from the wall, but that distance was possible if the mower was moving forward at maximum speed and her head did not hit the wall.Sydney Morning Herald - Latest News: “He said that distance was possible if the mower was being driven at maximum speed and going forward at 2.4 metres per second, and with absolutely no contact of her head on the wall.”
- SupportedAckland answered, “In my opinion, no,” when asked whether Frances could have hit her head on the rock and been 1.8 metres from the wall.Sydney Morning Herald - Latest News: “Ackland answered: “In my opinion, no.””
- SupportedThe defence says Frances’s death was a tragic accident, and Crawford has pleaded not guilty to murdering her.Sydney Morning Herald - Latest News: “Robert Crawford, 49, has pleaded not guilty to killing wife Frances at their sprawling property in rural south-east Queensland in July 2024. His defence team has told the jury Frances’ death was a tragic accident”
- SupportedCrawford told police he last saw Frances alive about 9.45pm, and the court heard he called Triple Zero at 3.37am.Sydney Morning Herald - Latest News: “He told police he last saw his wife alive about 9.45pm.”