But it was all a hoax.
He walked over to a garden area and pretended to vomit, Judge Andrea Manuel explained during Robertson's sentencing hearing today.
"You took an opportunity to escape," she said.
Robertson then used a nearby dog kennel to springboard over a fence, the court heard.
"Police tried to chase you but they were unsuccessful," the judge said.
The incident sparked a manhunt as police appealed to the public for sightings of the 28-year-old.
The search for Robertson came after an earlier incident on August 24, when he was stopped by police in a Ford on Federal St in central Auckland.
Despite being told to remain in the car he immediately fled, swearing at police.
"You were chased and eventually arrested near Aotea Square," Judge Manuel said.
When searched he had a ziplock bag that contained methamphetamine, she said.
"You said to the police that you had just injected yourself with methamphetamine and you had freaked out and that was what prompted you to run from the police."
Later that same month, he failed to return a BMW he had borrowed from a friend when he was supposed to.
Earlier this year, on June 30, police also found him in the driver's seat of a Ford.
He was slumped over, unconscious and refused to give police a blood specimen.
"Police found methamphetamine in a ziplock bag in a satchel on the front passenger seat," Judge Manuel said.
When sentencing Robertson, Judge Manuel took into account what she said was genuine remorse and an early guilty plea.
She imprisoned Robertson for 17 months for unlawfully getting into a motor vehicle, escaping custody, breaching release conditions and possessing methamphetamine.
He will be subject to six months release conditions.
Auckland City District Commander, Superintendent Karyn Malthus, previously said it was "very disappointing" that Robertson had been able to flee from police during the September incident.
She said it would form part of the national review of custody and transport of prisoners.
That review had been launched in August by Police Commissioner Mike Bush after two high-profile escapes occurred within a week.
At the time he said police managed tens of thousands of prisoner movements every year - most without incident.
"When something does go wrong we need to learn from it and, where appropriate, make changes so that it does not happen again."
