A part-time police officer lost his job after attempting to travel on a train without a ticket.
He was among 92 rail passengers caught by operator Translink last year.
A recent increase in the number of cases on the line to Jordanstown was linked to the start of the new university term.
The policeman's excuse when challenged was: "I am a part-time police officer, so I don't have to pay."
Translink also revealed the top excuses used by passengers for travelling on trains without paying for their tickets.
Claims that tickets have been lost and passengers are only travelling one stop feature on the list, as does flushing the ticket away because of a lack of toilet paper onboard trains.
Last year, 22 rail passengers were identified for ticketing irregularities which resulted in fines totalling £2,508.
In addition, 70 penalty fares for fare evasion were issued by rail staff resulting in fines totalling £1,579.40.
Hilton Parr, head of customer services at Translink NI Railways, said: "We've really heard every excuse under the sun from passengers.
"The majority of our customers are honest and pay the correct fare and as such it is only right that we take a tough line with those who try to fare dodge – the point I would make is that no matter who you are, if you want to travel on our services you have to pay."
The average fine issued to fare evaders in 2012 was £20 plus the value of the ticket for the distance they travelled.