A boy became ill after coming into contact with Sergei Skripal the day he and his daughter were poisoned with Novichok, an inquiry was told.
The Dawn Sturgess Inquiry was shown CCTV footage on Monday of Mr Skripal interacting with the child, who gave him bread to feed ducks in Salisbury.
The youngster, along with two others, then reported falling ill, the BBC reported - but did not have any trace of the dangerous chemical on them when they were tested.
The inquiry is ongoing into the poisonings on March 4 2018, which later claimed the life of Dawn Sturgess after she accidentally came into contact with the chemical weapon.
Ms Sturgess, 44, died after she was exposed to Novichok, which was left in a discarded perfume bottle in Amesbury, Wiltshire, in July 2018.
CCTV showed Sergei and Yulia Skripal driving into Salisbury, handing the boy bread to feed the ducks, having a drink in a local pub and heading to Zizzi restaurant.
Met counter-terror commander Dominic Murphy told the inquiry that the information had helped detectives narrow down the timing of the poisoning, by allowing them to estimate when Novichok was applied to the Skripals’ front door.
The inquiry also heard separately from a former chief nurse of the British Army, one of the first to attend to the Skripals, who said any suggestions that her role was connected to the incident are "malicious".
Alison McCourt said she had coincidentally visited Salisbury with her family on March 4 2018, because her children had wanted to go to a Nando's.
Ms McCourt, who left the army in 2022, responded to a document published by the Russian Embassy which said there had been "no attempt to explain" the "extraordinary coincidence" that she had been in the area at the time.
Responding to the Russian Embassy document from March 2023 titled Salisbury: Five Years of Unanswered Questions, Ms McCourt said in a witness statement: "I confirmed that as at March 4 2018 I was employed as chief nurse of the British Army. I subsequently left the army in 2022.
"On Sunday, March 4 2018, I was off duty and in my own time, I had travelled to Salisbury with my family for a family day out.
"That particular destination for our trip had been chosen by my children - they had wanted to travel to Salisbury because it had a Nando's.
"My preference had been to visit another town in the area, in a different restaurant, but I had given in to my children, so we ended up going to Salisbury.
"No person outside of my family was aware of our decision to travel to Salisbury that day - a decision which had been made spontaneously."
Ms McCourt said she would not have exposed herself or her daughter to the risk of coming into contact with Novichok if she was aware the Skripals had been poisoned with the nerve agent.
Her witness statement, which was read by counsel to the inquiry Francesca Whitelaw KC, continued: "I had no prior knowledge of the individuals on the bench - I had never seen them before in my life, nor did I know who they were.
"In fact, having seen the couple on the bench, my initial instinct had in fact been not to get involved as it looked to me as if they were under the influence of drugs.
"It was only the chiding of my daughter that made me think I ought to go to their aid.”
Ms McCourt insisted her involvement in the incident was as a "first responder member of the public".
"Any suggestion to the contrary is false and malicious,” she added,
The inquiry continues.
