British Transport Police is hunting two men who took a taxi from Northampton to Wellingborough but refused to pay when they arrived.
The incident happened on Sunday, July 7, at about 9pm, but only released the information today.
PC Ian Thompson said: “Two men caught a taxi from Northampton to Wellingborough train station.
“When they were dropped off at the station, they refused to pay the fare that had been agreed with them at the start of the journey.
“They then entered the station before walking off towards the town centre.”
Anyone who can identify the men can call the British Transport Police on 0800 405040 or text 61016 quoting reference B7/NEA of 20/08/2013.
Alternatively, information can be given to Crimestoppers anonymously on 0800 555 111.