The crash and explosion killed 47 people and destroyed a large swath of the downtown area.
The runaway train belonging to the Montreal, Maine & Atlantic Railway rolled into town carrying volatile crude oil, derailed and exploded in the wee hours of July 6.
Police spokeswoman Aurelie Guindon says the investigation was officially completed on Saturday and the case is now in the hands of the province's director of criminal and penal prosecutions.
Neither the Crown nor police would discuss the results of the probe.
Police said last summer their investigation would focus on the possibility of criminal negligence.
A spokesman for the Crown's office said the file is in the hands of a team of prosecutors, who have been working with police since the beginning.
Crown spokesman Jean-Pascal Boucher said his office will leave it to the prosecutors to review the file and that there is no timetable for potential charges.