Scotland Yard investigators traveled to Moscow this week as part of their probe into the Nov. 23 death by radioactive poisoning of former KGB spy Alexander Litvinenko . Although the Kremlin approved the British investigation, it has made it clear that the Russians are in charge and that any extradition request would be denied. For those reasons, and others, the British investigators have little chance of achieving a break in the case while in Russia — and even if they were to identify a suspect, it is highly doubtful that anyone would eventually be brought to trial. Russia, meanwhile, said Dec. 7 it will launch its own investigation into the case — even hinting at sending its own investigators to London — though the move could be aimed at addressing international public opinion rather than truly getting to the bottom of the Litvinenko killing.