A man accused of murdering the "love of his life" lied about how his partner died because "he didn't want to make her out to be a psycho", a court has heard.
Michael O'Connell, 43, faced the ACT Supreme Court on Tuesday for the first day of his jury trial.
The Coombs man has pleaded not guilty to murdering his "on-again-off-again" partner Danielle Jordan by allegedly throwing her from the bonnet of his moving vehicle.
Both the prosecution and defence agree O'Connell was not truthful when he originally told authorities and friends the woman fatally hit her head by falling down the back steps of her home.
"He told some silly lies about what happened," defence barrister Jon White SC said on Tuesday in his opening address.
The parties disagree on whether O'Connell was aware Ms Jordan was on his vehicle while he drove, her location on the moving car, and whether the man was recklessly indifferent to the woman's life.
The jury must also consider the alternative charge of manslaughter.
The incident in question occurred in the early hours of April 15, 2022, in the suburb of Melba where the deceased woman lived.
Prosecutor Mike Smith said O'Connell and Ms Jordan argued a number of times on the morning in question in the presence of a 13-year-old witness staying in the woman's apartment.
O'Connell allegedly returned about 4am but soon again left, followed to his car by Ms Jordan and the girl, who described the man to police as "schizing it", or acting angrily.
Prosecutors claim the woman hopped onto the bonnet of the man's black Mitsubishi Triton ute in one of multiple attempts to stop him from leaving.
Their case is that O'Connell drove about 200 metres with Ms Jordan on the ute's bonnet, reaching an estimated top speed of 63kmh.
The man allegedly stopped suddenly around the corner from the apartment, with the sound of screeching tyres heard on CCTV footage captured by cameras at a nearby home and played in court on Tuesday.
"She fell from the bonnet and suffered a catastrophic and ultimately fatal head injury," Mr Smith said.
The young witness, who did not see this occur but ran to the site of the incident shortly after, told police she saw Ms Jordan lying on the road towards the back of the vehicle.
O'Connell allegedly picked her up and placed her in the passenger seat.
"Michael, what the f--- did you do?" the teenager allegedly asked.
"I'm so sorry, mate ... she just fell off, I don't know what happened," he allegedly replied before driving Ms Jordan to Calvary Hospital.
The woman died in hospital two days later.
Jurors heard O'Connell's version of events was that Ms Jordan hopped off the car bonnet before he drove away but she caught up and jumped onto the ute's back tray.
His barrister said the woman's presence on the car could have been missed as she only weighed 46kg and was the size of a "small jockey".
O'Connell is said to have told police he stopped and exited the car after realising the woman was on the vehicle but she "slipped and fell" onto the road.
Mr Smith will try to prove O'Connell committed the alleged act and caused the death of Ms Jordan despite foreseeing the possibility she would die.
The prosecutor also told jurors they should take the man's "deliberate" lies into account when considering his version of events.
"Tell everyone that she fell down the stairs," O'Connell allegedly told the 13-year-old witness after the incident.
Mr White acknowledged the "terrible tragedy" of Ms Jordan's death but asked jurors to question the premise his client drove with the woman on the car bonnet and came to a sudden holt to dislodge her.
He noted prosecutors did not claim his client intended to kill his partner, whose behaviour prior to her death the barrister described as "unpredictable and obsessive".
Mr White also told jurors he would call into question the reliability of the sole eye witness, who offered the only evidence supporting Ms Jordan being on the car bonnet.
"She not unnaturally blamed Mr O'Connell for the death of her good friend," the barrister said.
