The case was prompted by a complaint from a customer who reported that two plain-clothes security guards had grabbed her by the neck and dragged her 50 metres after she bought two bottles of herbal cough syrup at a Tsim Sha Tsui branch.
A source confirmed on Thursday that police had received a report on the incident and were investigating it using “all available methods”.
In a social media post on Tuesday, a woman surnamed Leung said she had paid HK$80 for the items at a self-service counter but was intercepted by two women who accused her of stealing the syrup.
One of the women, who was later found to be an undercover store detective, grabbed her neck from the back, while the other dragged her backpack, towing her back to the store, Leung said.
But Leung produced the receipt, which proved her purchase.