If Nick Priest was right and the trail of radiation really was like following a burglar's footprints in the snow, the Metropolitan Police simply had to establish where the footprints were and which way they pointed. But to Peter Clarke things were not looking quite so simple. The ‘footprints’ he had found looked suspiciously like they went round in circles, as if there might be more than one radiation trail, and sometimes seemed to lead backwards instead of forwards.
The first important discovery Clarke's men had made was that radiation traces were not confined to the locations visited by Sasha Litvinenko: another, independent polonium trail followed the footsteps of Andrei Lugovoy and Dmitry Kovtun. The police knew there was contamination at the site of their meeting in the Pine Bar; they knew there was contamination at locations they visited after that meeting; and - crucially - they had now discovered there was radiation at several locations they had visited before the Pine Bar meeting. The reason this discovery caused so much excitement was that radiation at or after the meeting with Litvinenko could have come from Sasha himself: it could have rubbed off on the two Russians in the way Nick Priest and others had outlined. But radiation on Lugovoy and Kovtun before the Pine Bar meeting could only have come from them.
Scotland Yard now had a lead to follow and two potential suspects to investigate. Clarke's priority team was charged with reconstructing Lugovoy and Kovtun's movements and quickly established that they had been coming in and out of Britain for many weeks, if not months. Yuri Felshtinsky reported that he had seen Lugovoy on the evening of 12 October outside Henry's Cafe Bar at number 80 Piccadilly. Worryingly, the British police could find no passport or immigration records for him at that time and initially suspected Felshtinsky had mixed up the dates, but Felshtinsky had kept the receipt for a cash machine transaction he made that night and it located him exactly where he said he was.
Lugovoy and Kovtun's next appearance seems to have been on 16 October, and this time there were official records of their movements. From passport and immigration lists detectives were able to establish that the two men flew from Moscow to London on a flight operated by the Russian airline Transaero. Scotland Yard knew the plane was a Boeing 737 with the registration EI-DDK, but when they approached Transaero with a request to examine the plane, the company refused. That night Lugovoy and Kovtun stayed at the exclusive Parkes Hotel, with rooms starting at £199 ($380), in swanky Knightsbridge just round the corner from Harrods. When police arrived with a forensic team, they were shown to the two rooms the men had occupied and quickly discovered that both were contaminated with radiation. A table in one room and a door handle in the other were showing traces of alpha energy, the distinctive signature of polonium. Two days later the men returned to Moscow. Again Transaero would not allow the plane they had used to be examined. But the discovery of radiation at the Parkes Hotel was of vital significance to the police: it proved that the polonium was in the UK as early as 16 October.
On 25 October Lugovoy again flew from Moscow to London, this time on a British Airways flight, number BA875. The plane, GBN-WX, was tested by detectives and Health Protection Agency staff and found to show traces of radiation on one seat and an overhead luggage locker. Scotland Yard will not give any further details, but unnamed sources quoted by the BBC said that the locker may have been contaminated by Lugovoy's briefcase and that a second consignment of polonium may have been brought to London that day. Certainly, there was no doubt about the hotel where Lugovoy stayed. The Sheraton on Park Lane, another upmarket hotel in another upmarket area, was tested and found to show high levels of contamination. In particular, room 848 on the eighth floor had radiation levels as high or higher than those found in the Pine Bar. The Metropolitan Police moved quickly to contact all guests who had used the room after 16 October and urged them to undergo a medical examination. The corridor on which room 848 is located was sealed off and remained so over two months later. On 28 October Lugovoy returned to Moscow on the same BA plane on which he had arrived.
That same day Dmitry Kovtun flew from Moscow to Hamburg, where his German ex-wife and their young child live. He flew on an Aeroflot plane, which the Russian authorities would not release for radiation testing, but German police were able to examine the Hamburg flat he and his wife stayed in that evening. It was contaminated, and so was Kovtun's BMW in the parking lot outside. The German authorities concluded that Kovtun had brought polonium with him from Moscow and said they wished to question him on suspicion of importing radioactive material. Hamburg's Chief Prosecutor, Martin Koehnke, announced that he considered there was reason to suspect Kovtun may have been among those responsible for Litvinenko's death.
On 31 October Kovtun and Lugovoy both flew to London for their final visit. The British Airways plane taken by Lugovoy, GBNWB, was again found to be contaminated; the polonium trail now strongly suggested that the isotope had been brought into London repeatedly. That evening Lugovoy went to the Down Street offices of Boris Berezovsky and the two men shared a bottle of wine. Berezovsky had employed Lugovoy since the mid-1990s, first as a bodyguard and later as a security consultant. Their relationship had continued after Berezovsky fled to London; they were long-term acquaintances and evidently close enough for the always busy Berezovsky to spare time for a drink and a chat with him. It was a relationship that would be closely examined when police investigations began to point towards Lugovoy as a suspect in the Litvinenko murder.
When Peter Clarke's men examined Berezovsky's office, the chair on which Lugovoy had sat that evening was found to have very high levels of contamination. After the meeting Lugovoy went back to the Millennium Hotel on Grosvenor Square, where he was staying along with Dmitry Kovtun and Vyacheslav Sokolenko. Police later found two bedrooms, numbers 101 and 441, to be heavily contaminated; they will not say who slept in which room but there was a strong suggestion that Sokolenko's room was not one of those affected.
Having followed the radioactive footprints in the days leading up to 1 November, the police were now concentrating on the day itself. They knew Litvinenko had had two scheduled meetings, and from a detailed examination of CCTV footage and cash-register receipts had been able to establish their order and timings. The Itsu meeting with Scaramella had taken place shortly before 3.30 p.m. and the Pine Bar encounter with Lugovoy and Kovtun began an hour later at 4.30. Would the radiation trail point to Sasha's murderer?
The first measurement for 1 November was taken from the Oyster card Litvinenko had used to pay for the bus journey from his home into central London. An Oyster card is a season ticket in the form of a top-up credit card; the passenger touches it against an electronic reader every time he takes a bus or an Underground train, and the card creates an electronic record of the times and routes of all journeys taken. In the case of Litvinenko's ride on the number 134 bus the card allowed detectives to trace which vehicle he had travelled on and who was driving it. They tested both Litvinenko's card and the bus itself, and found no radioactivity on either. This was a strong indication that Sasha had not been poisoned before the time his bus journey ended, at 11.30 a.m. on 1 November. Then Litvinenko went into a newsagent's shop and browsed the shelves. He bought a bottle of water and picked up a newspaper. Again, the shop was tested and no trace of polonium was found on either the premises or the objects Sasha had touched.
But next came the Itsu sushi bar, and this time there was plenty of evidence of radiation: detectives found a table and two chairs unmistakably contaminated with alpha energy. For the police it was an important discovery and raised immediate suspicions: this was Litvinenko's first recorded meeting after the negative tests of the bus journey and the shop, and it was the first location to link him to the presence of radiation. He was clean before the Itsu meeting but apparently contaminated afterwards.
This was circumstantial evidence that the sushi bar was the most likely scene of the poisoning. In addition, Litvinenko himself had initially fingered Scaramella as the man he suspected of attacking him. The day after they got the results from the sushi bar, the British police took Mario Scaramella into ‘protective custody’. A test on a urine sample he provided was sent to the Atomic Weapons Research Establishment at Aldermaston and swiftly returned with sensational news: it had tested positive for massive polonium poisoning. The evidence was building…