Investigators probing the nerve agent scare at a Salisbury restaurant are likely to consider if it was the result of a hoax.
Two people were taken to hospital after apparently becoming ill at the Prezzo Italian restaurant on Sunday, sparking fears they had been poisoned by Novichok.
Emergency services declared a major incident and the restaurant and surrounding area were sealed off.
The pair – identified as Russian-born model Anna Shapiro, 30, and husband Alex King, 42 – tested negative for the nerve agent and have been discharged from hospital.
Mr King is reported to have once pulled off a prank that saw him infiltrate a meet-and-greet with the Prince of Wales and Duchess of Cornwall at a 2006 film premier.
A police source told the BBC that they “can’t rule anything in or out” until investigators speak to Mr King about Sunday’s events.
Witnesses described a scene like “Armageddon” as police and emergency services, some wearing protective suits, rushed to the scene.
Ms Shapiro told the Sun newspaper her husband went to the toilet and she grew concerned when he did not return after 15 minutes.
“I headed up and saw him lying on the floor near the sinks,” she said. “I ran downstairs for help. I was panicked.”
Both were taken to Salisbury District Hospital.
Lorna Wilkinson, director of nursing at the hospital, said: “Both patients are now medically fit and there is no need for them to be in hospital.
“While this incident did not involve nerve agents, it was still clearly very stressful for our staff who, once again, demonstrated the very best of the NHS.”
Wiltshire Police said it is now conducting a “routine investigation” into the incident.
“The woman from the restaurant has been interviewed once and is likely to be spoken to again.
The next step is to speak to the man involved,” a spokesman said.
A spokesman said: “Once again, we would like to thank Salisbury’s emergency services, our neighbours, our customers and our team for their support and understanding.”
The incident came amid heightened tensions in Salisbury in the wake of the poisoning of former Russian spy Sergei Skripal and his daughter, Yulia, in March.
The Prezzo is a short walk from Queen Elizabeth Gardens, which was until recently closed off after 44-year-old Dawn Sturgess was fatally poisoned by the nerve agent in June.