The 26-year-old couldn't remember if he was the one behind the wheel of his mother's car when it was parked by the tracks at a small town station in the north-eastern canton of Saint-Gallen, local police said.
Police were awaiting results of blood and urine tests to see if the unidentified man, who they found at his home Tuesday, had been under the influence of alcohol or drugs.
A train conductor spotted the locked and damaged car around 7am on Tuesday and alerted police, triggering an elaborate operation to remove the car, which had to be lifted out by crane.
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Power along the whole line of the small private Südostbahn railway network also had to be cut during the operation, police said.