Three years after losing her son in one of Australia's most high profile missing child cases, a tearful Karlie Tyrrell has blamed her panic attacks for spitting at a police officer.
The troubled biological mother of toddler William Tyrrell had pleaded guilty to assaulting an officer and using offensive language in public during an incident at a suburban Sydney shopping centre last month.
The emotional 29-year-old, who has a long criminal history, faced Burwood Local Court on Monday but won't learn her fate until March 19 when sentencing proceedings continue.
Her three-year-old child, widely pictured wearing his iconic Spiderman costume, disappeared while playing in his foster grandmother's yard south of Port Macquarie in September 2014.
The boy was removed from the care of his birth mother as a seven-month-old following domestic violence and drug use concerns.
Police arrested Tyrrell at the Top Ryde mall around 9pm on December 22 after security guards reported her acting aggressively towards customers and repeatedly swearing in front of children.
Police facts say the accused became very angry when an officer asked one child in her company about marks on his legs, saying "none of your f***ing business".
She then spat on a second female officer's right eyebrow and cheek after shouting "Ryde coppers lost my son you c****".
Tyrrell wiped tears from her eyes in court earlier on Monday before a pre-sentencing report was ordered.
Court documents reveal an extensive rap sheet of previous crimes including assaulting officers and civilians, resisting arrest, damaging property, shoplifting, breaching bail and using offensive language.
In a handwritten note from Tyrrell also tendered on Monday, she said her mental health problems were behind the assault.
"I recently found out I suffer from panic attacks which played a major part into my behaviour but I'm not making any excuses," she wrote.
Police spent days scouring bushland and neighbouring houses in Kendall after William vanished to no avail and an unprecedented $1 million reward for information leading to his return remains on offer.
William would now be six, and his carers remain hopeful of finding him alive.