Officers wearing protective clothing are to carry out enquiries at the Boots store in Amesbury as part of the investigation into the Novichok poisoning in Wiltshire.
Dawn Sturgess died on July 8 after she and her partner Charlie Rowley, 45, both fell ill at the end of June.
It is believed they were exposed to the deadly nerve agent after handling a contaminated bottle later found in the home of Mr Rowley, who was discharged from Salisbury District Hospital last week.
Wiltshire Police said officers would visit the shop on Stonehenge Walk on Thursday morning to collect CCTV as part of the inquiry. Protective equipment will be worn on a precautionary basis, the force added.
Mr Rowley and Ms Sturgess were victims of the second nerve agent incident in four months following the case of Sergei Skripal and his daughter Yulia.
They were found unconscious on a park bench in Salisbury in March.