Detective Sergeant Nick Bailey said poisonings in March 2018 "took so much from me" as he announced his departure from Wiltshire Police.
Trump described the situation as "tragic", adding that while he hadn't seen "any proof" of poisoning he would investigate.
The house is the last site in Salisbury to be decontaminated of the deadly nerve agent.
Foreign Secretary Jeremy Hunt promised "tough action" on Russia.
A policeman who came into contact with the deadly substance has told of his ordeal in his first interview since the attack.
Strong words from the Russian President.
Anna Shapiro says her fears were genuine.
US, France, Germany And Canada Have 'Full Confidence' Salisbury Attack Suspects Were Russian Intelligence Operatives
Russia urged to disclose details of its Novichok programme after UN Security Council meeting.
Brother of victim says nerve agent destroyed his immune system.
Detectives trained to memorise faces are trawling CCTV footage.