Nine months after a young woman fell from a party bus in downtown Vancouver and died, police have wrapped up their investigation and decided not to recommend criminal charges.

Chelsea Lynn Mist James, an assistant teacher from Langley, was out for a birthday party the night of Jan. 9 when she tumbled out of the Silver Lady Limousine vehicle and was crushed.

She was 23 years old.

Police spent the better part of a year investigating the tragedy, bringing in commercial vehicle experts and engineers to conduct full inspections of the party bus, and released their findings Tuesday.

According to investigators, the victim lost her balance after the driver made a left turn from West Hastings to Burrard Street and stumbled into the stairwell against the pneumatic door.

The door then opened and James fell onto the street, where she was run over by the same vehicle.

Police determined the main factors in the tragedy were a mechanical malfunction and low operating pressure with the bus's pneumatic door.

"The latches and air pressure involved should have kept that door closed, and it did not," Const. Brian Montague said.

After consulting with Crown, police said they will not be recommending criminal charges in the accident, but the owner and driver of the vehicle were fined under the Motor Vehicle Act and could be subject to a potential lawsuit.

That's of little consolation to James's family, who are still grieving their devastating loss.

"Chelsea did nothing wrong and she paid the price," the young woman's mother, Shelly James, told CTV News. "That's the hard thing about it… there's no accountability."

Silver Lady Limousine has yet to respond to the death.

Documents released by the B.C. government show the party bus in question underwent two safety inspections since 2014, and in one of them the door was not opening properly. The company either repaired or altered it, and the bus passed another inspection in 2015.

Though the province strengthened licensing regulations and fines for the party bus industry last year, James's family is calling for more stringent rules around mechanical inspections as well, hoping to save others from experiencing their pain.

"If we can save families from going through the hurt that we go through, Chelsea would be proud," her mother said.

With files from CTV Vancouver's Scott Roberts