CCTV footage, a bag of tools and a rubber glove helped police arrest the woman responsible for burning down Cleveland Ambulance Station four years ago.
Jodie-Anne La Spina, 27, was sentenced to three years' imprisonment in Brisbane District Court on Tuesday after pleading guilty to committing the "revenge" attack on the station.
But she was released on probation on Friday, having already spent four years in custody waiting for her trial.
La Spina was a 23-year-old paramedic student when she broke into Cleveland Ambulance Station on October 26, 2010.
The Wellington Point woman had undertaken work experience at the station, but had then failed a mandatory psychometric test for entry into the Queensland Ambulance Service.
Armed with a lighter purchased from a service station only minutes before and a bag of tools, she's believed to have used sanitary handwash with a high alcohol content to set the station on fire.
She then stole one of the ambulances, dumped it at Dundas Street West in Ormiston, and set it alight.
The court heard the cost of the crime, including demolition, reconstruction and replacement of vehicles, totalled about $6 million.
A motorbike left near the dumping site was used as an alibi by La Spina, who claimed the ambulance thief had crashed into her while she was riding along the street.
The principal investigator of the crime, Cleveland Detective Sergeant Graham Kershaw, said officers found La Spina near Dundas Street shortly after the arson.
A search unearthed the breaking tools in her bag and a blue rubber glove, similar to one found in the ambulance.
CCTV footage from the service station also showed La Spina purchasing the lighter just before the arson attack.
"We were able to link her through the revenge theory and work experience," he said.
"We took the same methodical approach we would do for any other major investigation."
The former Redlands College student spent 20 months in a psychiatric facility while her lawyers argued for her to be tried through the Mental Health Court.
However, she was found to be of sound mind and a trial was set to be heard in the Brisbane District Court on November 18.
La Spina pleaded guilty to two counts of arson and one count of unlawful use of motor vehicle the Thursday before the trial was due to start, changing it into a sentencing hearing.
Judge Hugh Botting sentenced her to three years' each for the two arson offences, to be served concurrently, and three years' probation for theft of the ambulance.
He took into account the time La Spina spent in custody before sentencing and the likelihood she had not intended to injure anyone through her actions.
The new ambulance station officially opened in September this year, an event Sergeant Kershaw described as akin to "a phoenix rising from the ashes".