The employee was disabled and didn't have to go through the body scan for this reason. He is believed to have made 800 million South Korean won worth about 712.568$ he has been doing this to pay a gambling debt of 900 million won 801.639$. He has been stealing phones from December 2014 - November 2016 The phones in question were a bit older and not meant for sale but for developers to look at updates. They noticed a few of the stolen phones being for sale in Vietnam that made them investigate it.
Source: The Investor (http://www.theinvestor.co.kr/)