"This latest horrendous turn of events has only served to strengthen the resolve of our investigation team as we work to identify those responsible for this outrageous, reckless and barbaric act", counter-terrorism police chief Neil Basu said. "Charlie is still very unwell and will continue to require specialist, round-the-clock care here at Salisbury District Hospital".
Police are now searching for a "contaminated item" that could have exposed the pair to the nerve agent, which is the same substance found in the poisoning of former Russian spy Sergei Skripel and his daughter Yulia in nearby Salisbury.
He said 100 detectives were working on the investigation, which was now focused on on Ms Sturgess's address within John Baker House in Salisbury, Mr Rowley's address in Muggleton Road, Amesbury. and an area in the Queen Elizabeth Gardens in Salisbury.
At the weekend, his girlfriend Dawn Sturgess, 44, tragically died after also being poisoned.
The British government has accused Russian Federation of being behind the attack on Mr Skripal, who settled in the United Kingdom after a spy swap.
Police searching for the source of a Russian nerve agent that killed a woman and sickened three others have seized a auto about 40 miles away from the original investigation site.
They both then fell ill on Saturday 30 June, and Ms Sturgess died eight days later.
"The brutal reality, however, is that I can not offer you any such assurances or guarantees at this time".
"I would need a forensic link to be definitive, but this is a very rare substance banned by the worldwide community and for there to be two separate distinct incidents in one, small English county is implausible to say the least".
Police are continuing to hunt for a contaminated container which they believe was handled by the pair.
"I am hoping Charlie recovers, and when he recovers he will be able to tell us and perhaps shed some light on it which will narrow our search dramatically".
Six locations visited by the couple have been cordoned off, including Mr Rowley's home on Muggleton Road in Amesbury, a Boots shop and a baptist church.
The BBC understands the white Audi belonged to a paramedic who had been with Ms Sturgess in an ambulance when she fell ill.
Ms Sturgess, who had a daughter aged 11 and two sons aged 19 and 23, had...
A tweet by police said, "the public should not be alarmed by this".
- David Lee in Russia: Gareth Southgate could be England's salvation
- Son of slain anti-Taliban politician among 20 dead in Pakistan blast
- Russian Federation recall Denis Cheryshev against Croatia
- Trump administration announces $US200 billion in extra China tariffs
- Amal Clooney's Husband Rushed to ER After Scooter Crash
- France grinds way to World Cup final, edges Belgium
- Race Begins to Acquire Movie and Book Rights to Thai Cave Rescue
- Trump's Supreme Court nominee Kavanaugh woos Senate
- Chelsea's Eden Hazard: Playing for Real Madrid is everyone's dream
- Trump administration freezes Obamacare payments, citing court decision