Hundreds of travelers’ bags at Changi Airport were sent to the wrong destination after an airport baggage handler, Tay Boon Keh, deliberately swapped the luggage tags of a total of hundreds of bags almost every day for three months from November 2016.

An employee of industrial equipment supplier Lian Cheng Contracting, a Changi Airport Group subcontractor, Tay was charged with 286 counts of mischief on Tuesday. Tay represented himself in court and plans to plead guilty when he returns to court on 17 Oct.

Although no motive was given for Tay’s acts, it was revealed that his shenanigans began when he first switched the tag of a Penang-bound bag with another bag tag on 8 Nov 2016. Tay subsequently showed his handiwork on numerous other bags, affecting travelers flying on Singapore Airlines, SilkAir and Lufthansa.

A representative from Changi Airport told reporters that this was an isolated case of mischief, and that aviation security has not been seriously breached. The group has also increased CCTV surveillance and patrols in baggage handling areas.

Tay could face up to a year in jail and/or a fine for each of the 286 charges if convicted.