After a six-month investigation, a report has now been submitted to the Procurator Fiscal in Hamilton in connection with the accident, which occurred near Biggar on March 31.
However, no person is named in the report. Although it rests with the Crown Office to decide on any criminal charges, it is unlikely any will follow.
Natasha (17), from Cleghorn, was one of 39 sixth year pupils from Lanark Grammar School who had set out in blizzard conditions for an Easter break at Alton Towers theme park in Staffordshire.
Just 12 miles after setting out, the coach being driven by 60-year-old driver Raymond Munro came off the A73 south-west of Biggar around 6am.
The vehicle crashed through a bridge parapet and came to rest on its side, 10 feet down in fields and partly under water.
It is believed Natasha was thrown from the vehicle and was only discovered after she failed to register in a head count conducted by teachers after the accident.
Some parents had criticised the decision to set out on the trip, given that it was snowing heavily that morning.
Driver Mr Munro was detained in hospital for several weeks and said to be “beside himself with grief” over Natasha’s death.
At her funeral in Lanark in April, hundreds of friends and relatives turned up wearing the colour purple, Natasha’s favourite.
So, too, did her parents, Jacqui and Gordon. The coffin was also coloured purple.
A spokeswoman for Strathclyde Police said: “A report has been submitted to the procurator fiscal.”
It is still possible that the Crown may order a Fatal Accident Inquiry, which will examine all aspects of the tragedy.
No-one was available at coach company Photoflash to comment on the development.
The fatal trip was organised by Natasha's school, which comes under the responsibility of South Lanarkshire Council. A spokeswoman for the local authority said last night: “We await the conclusion of the Procurator Fiscal following the submission of the Strathclyde Police report to the Crown.”