Now, the two men have appeared on Russian TV in an freaky interview that included their denials - but also indirect questions about their sexual preferences, awkward stares and accounts of the weather in the quaint English town of Salisbury in early March 2017.
They are accused of conspiracy and the attempted murder of Skripal and his daughter, Yulia, and of a police officer who was investigating the poisoning.
Their first public appearance, a September 12 interview with the Kremlin-funded RT channel, contained a few head-scratchers.
"Salisbury?" their interviewer asked. "We didn't have it", Mr Boshirov said. "There's the famous Salisbury cathedral, famous not only in Europe but in the whole world, it's famous for its 123m spire, it's famous for its clock, one of the first ever created in the world that's still working". They said they were not, and actually work in the sports nutrition industry.
Britain is accusing Russian Federation of "lies and blatant fabrications" after the prime suspects in the Salisbury nerve agent attack claimed they visited the United Kingdom as tourists. We have repeatedly asked Russian Federation to account for what happened in Salisbury in March.
So what were these two men really doing in Salisbury?
Scotland Yard believes the pair were using aliases after the men claimed Petrov and Boshirov were their real names.
"The police have set out very clearly the evidence against these two men, they are wanted men and we have taken all steps to ensure they are apprehended and brought to justice in the United Kingdom if they ever again step foot outside of Russian Federation", he added.
"We examine the market, look if there is something new - some biologically active additives, amino acids, vitamins, microelements", the two said.
Boshirov said they "maybe approached Skripal's house" while they walked around the city, "but ... didn't know where it was".
British officials decried the interview, calling it "risible".
A police officer who visited the home of the Skripals shortly after the attack, Nick Bailey, was also left critically ill from exposure to the substance. One of the bystanders later died from the Soviet-era nerve agent after she discovered it in a park disguised in a perfume bottle.
British investigators say the poison was transported in a fake perfume bottle.
Asked by Simonyan whether they had the perfume bottle that had been shown as evidence by United Kingdom authorities, Boshirov said: "Is it silly for decent lads to have women's perfume?" Margarita Simonyan, RT's editor-in-chief, who conducted the interview, said on Twitter that "their answers are their responsibility" and it's up to viewers to decide whether to believe the men, who were "extremely nervous and sweating". The station said it would air more of the interview later.
The two added that they had planned to visit London on their trip, but a snowstorm hindered their plans.
"More importantly, they are deeply offensive to the victims and loved ones of this horrific attack", he said. The Skripals were found collapsed on a park bench at 4:15 p.m.
"At 3pm on Friday, 2 March, the suspects arrived at Gatwick airport, having flown from Moscow on Aeroflot flight SU2588".
They also asked for an apology from the United Kingdom authorities, adding: "We just want this to be over".
"They then travelled on London public transport to Waterloo station and were in the area between approximately 6pm and 7pm".
Tests on the east London hotel room where the suspects had stayed showed contamination of Novichok.