Aides of Russian opposition figure Alexei Navalny said Thursday that German experts found Novichok nerve agent on a water bottle taken from the hotel room where he stayed before being poisoned.
The bottle appears to have been key evidence for Germany's conclusion that the 44-year-old lawyer and outspoken critic of President Vladimir Putin was poisoned with the military-grade nerve agent.
Specialists from a German military laboratory found traces of Novichok on a bottle of "Holy Spring" water Navalny left in his hotel room in the Siberian city of Tomsk, his spokeswoman Kira Yarmysh said in a video statement.
The discovery "means that Navalny was poisoned before he left the hotel and not in the airport or on the plane," Yarmysh said.
Navalny collapsed last month on a flight from Tomsk to Moscow after a campaign trip to support opposition candidates in local elections.
Previously aides had suggested he had been poisoned by a cup of tea he drank at an airport cafe.
The 44-year-old lawyer is being treated in a hospital in Berlin and on Tuesday said he was breathing for the first time without medical support.
Germany has said it has "unequivocal evidence" that Navalny was poisoned with a Novichok nerve agent and this week reported that labs in France and Sweden had confirmed the findings.
His ally Lyubov Sobol tweeted Thursday that it was "important to understand that there were traces of Novichok on the bottle in the hotel, (but) that doesn't mean Navalny was poisoned specifically by the bottle of water."
He stayed for three nights at Tomsk's Xander hotel, a modern four-star hotel, and also visited its restaurant, according to transport police.
Navalny's team, some of whom were staying at the same hotel, collected the bottle and other items from his room after hearing he fell ill.
Yarmysh posted video on Twitter of aides in gloves packing up items left in the hotel room in plastic bags.
"It was decided to take everything that could be hypothetically useful and hand it over to doctors in Germany," Navalny's aides said in a statement.
"It was obvious from the start that the Russian leadership would deny poisoning and the law enforcement authorities would not open a criminal probe and carry out an investigation," Yarmysh said.
Russia's Proyekt news site published a detailed investigation on Thursday, citing Navalny's aides.
It wrote that the water bottle was key evidence for German experts because Novichok would have remained intact while it was broken down in Navalny's body.
It said that aides collected an opened bottle of Svyatoi Istochnik, or Holy Spring, mineral water, a popular brand.
It cited an aide as saying Navalny does not remember when exactly he drank from the bottle.
One of Novichok's creators, Vladimir Uglev, told the site that Navalny's survival meant it was likely he only had skin contact with the poison, suggesting it was not in the water.
Navalny spent his last day in Tomsk except for an evening trip to swim in a local river, Proyekt reported.
Proyekt found that the door to Navalny's room was within view of two security cameras and transport police, who are carrying out a pre-investigation check into the circumstances have the footage.
Despite having evidence for an investigation, a month later, "a criminal probe has still not been opened," Yarmysh complained.
The anti-corruption campaigner's suspected poisoning has sparked sharp condemnation from Western leaders, who have called for a thorough investigation and for those responsible to be brought to justice.
Russia has dismissed "unsubstantiated claims" over the incident and said its doctors found no trace of toxins.
Germany has not released details of the evidence for Navalny's poisoning with nerve agent.
Russia has focused on Navalny's medical tests, saying its own medics did not detect poisoning and asking Germany to provide results of tests done there.