KEY POINTS:
LONDON - Detectives have isolated the moment at which former Russian spy Alexander Litvinenko came into contact with the radioactive contamination that killed him.
After re-tracing the route taken by Litvinenko on the day he fell ill, anti-terrorist officers now believe the ex-KGB agent was either poisoned in a Japanese sushi bar in central London or just before entering the restaurant. Litvinenko had visited the sushi bar to meet an Italian contact on November 1.
Detailed forensic analysis of Litvinenko's movements before he went to the branch of Itsu in Piccadilly have found no trace of radioactive contamination. This strongly suggests he was poisoned in the restaurant, where traces of nuclear material were found.
Litvinenko, 43, an outspoken critic of Russian president Vladimir Putin, died on November 24 after being contaminated with polonium-210.
The focus of the police inquiry is what happened at the Sushi bar where Litvinenko met Mario Scaramella, an Italian academic who denies having anything to do with the poisoning.
Scaramella, who runs an organisation that tracks nuclear waste, said this week he had been tested and was not contaminated.
He was questioned in London this week by anti-terrorist officers after he returned to Britain from Italy to help with the inquiry.
A waitress at the Itsu restaurant said Litvinenko had been served sushi in a sealed box, but that he did leave it to visit the toilet.
Scotland Yard pinpointed the Sushi bar after tracking the former KGB agent's movements from his home in Muswell Hill, north London.
By using information from his mobile phone records, Oyster travel card and CCTV footage, detectives plotted his route through London to Piccadilly tube station.
Locations along the way have been tested for radiation contamination, but all proved negative.
Ela Malek, 22, a Polish waitress who said she served Litvinenko, told the Sun he arrived alone before being joined by a man - Scaramella. She was convinced Litvinenko's meal could only have been spiked after it was presented to him.
"The food is prepared in the kitchen and is put in a box with a clear lid, which is sealed with a label.
"I know everyone in the kitchen and there's no way they would be involved in this. Once the box is sealed it is taken straight to the customer.
"At one time I think Litvinenko went to the toilet, leaving his food on the table. I suppose anyone could have slipped something in then."
Danger zones
The 12 locations where traces of contamination have been discovered:
* Itsu sushi restaurant, Piccadilly - Believed to be where Litvinenko was poisoned with radioactive Polonium 210. Litvinenko met Mario Scaramella, an Italian academic, for a meal on November 1, the day he fell ill.
* Millennium Hotel, Grosvenor Square - After the sushi meal Litvinenko met two Russian contacts - Andrei Lugovoy, a former KGB bodyguard who runs a security company, and a man named Andrei Lugovo.
* Litvinenko's home, Muswell Hill, north London - Accommodation provided by Boris Berezovsky, an exiled Russian millionaire and critic of President Putin.
* A car in Muswell Hill, north London - Used by a neighbour of Litvinenko to take him to hospital.
* Barnet General Hospital - Several hours after his meetings on November 1, Litvinenko complained of feeling sick and was admitted to the hospital in north London.
* University College Hospital - On November 18 Litvinenko was transferred to the hospital in central London as his condition deteriorated.
* 25 Grosvenor St - Traces of Polonium 210 have been found at this address which houses the headquarters of international security company Erinys, visited by Litvinenko.
* 58 Grosvenor St - Office buildings found to be contaminated, not clear what links with Litvinenko.
* 7 Down St - Traces of Polonium 210 found in the office of Berezovsky.
* Sheraton Hotel, Park Lane - Low level radioactive contamination found at the five-star hotel. One of Litvinenko's contacts is thought to have visited there.
* Low levels of radioactive traces found on two grounded British Airways Boeing 767 aircraft at Heathrow.
- INDEPENDENT
