The incident, which took place in the early hours of Tuesday morning and made headlines around the world, may end up being reclassified as a workplace safety crime.
"There's no longer reason to suspect her of any crime," prosecutor Pär Andersson told the TT news agency.
After searching her home, and speaking with relatives as well as emergency workers in contact with the woman after the crash, investigators concluded there was no longer any reason to believe she intentionally drove off in the train.
Andersson added the investigation revealed a number of "unfortunate circumstances" that allowed the woman to put the train in motion.
"The forensic investigation showed that there were a number of serious safety breaches on the train and where it was parked," the prosecutor's office said in a statement.
The Local's images from the scene of the crash
The investigation is now instead looking at whether the crash was a crime against Sweden's workplace safety laws in order to assess what responsibility the train operator had in causing the accident.
"If the investigation shows that there were workplace safety violations and there is a connection with what happened, that could be grounds for suspicions that a workplace safety crime has taken place," prosecutor Mats Palm told TT
Both Stockholm public transit operator SL and subcontractor Arriva hinted that the cleaning lady stole the train before crashing it through a barrier at the end of the line.
“I made clear from the beginning that all scenarios were possible. It’s unfortunate that she was depicted as a thief, and I’m truly sad about that," Tomas Hedenius, a spokesman Arriva, told The Local.
"I should have done more to make it clear that there are several possible scenarios. Obviously I didn’t do it enough.”
RELATED PHOTO GALLERY: More images from the scene of the crash
The train came to rest in a small block of flats about 30 metres from the end of the line, where it remains lodged in the ground-floor kitchen of one of the apartments.
As of Friday afternoon, the removal of the train wreck was still underway.
"We are still planning to remove the train and salvage the house next week. Not much has happened today except the preparation for this," Hedenius told The Local.
The cleaner, meanwhile, remains in serious but stable condition and it remains unclear when she may be well enough to speak with police.
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