Can a person that works in loss prevention stop you & ask to look in your bag once you have went outside of the store without a police officer

My wife & I was in a Georgia belk department store a couple of weeks ago & I put a $ 6.00 bath bomb in my bag at the cash register when she was buying a pair of jeans I thought she had paid for it when we walked out of the store a man approached me & said that he was in loss prevention & ask to look in my bag is that legal because he did not show me any type of is or badge nor did he have a police officer or anyone else with him ?