Transcript for A fierce critic of Vladimir Putin was found dead in South London

Overseas now and stunning new developments in a mystery death of a Russian dissident on British soil. Authorities confirming a critic of Russian president Vladimir Putin was murdered in his home in London. Putin already blamed for the nerve agent attack on an ex-russian spy. ABC's chief foreign correspondent, Terry Moran is in Moscow. Reporter: Counter terrorism police and hazmat-suited technicians swarm a home in south London. Another Russian victim in England, a fierce critic of Vladimir Putin. This man, Nikolai glushkov, a former top executive at aeroflot, the Russian airline, who fled Russia and claimed asylum in Britain in 2004, found dead Monday. Police say it was compression of the neck, strangulation, and they're now treating his death as a murder. Glushkov's killing came just over a week after Russian spy sergei skripal and his daughter were poisoned by a military-grade nerve agent in Salisbury, England. And today, British foreign minister Boris Johnson accused Putin personally in that attack. We think it overwhelmingly likely that it was his decision to direct the use of a nerve agent. Reporter: Russia that has denied any involvement. Putin today campaigning in a lab coat, ahead of Sunday's presidential vote and state TV this week showing a fawning documentary with this exchange. "What is not possible to ever forgive?" Terry Moran ABC news. And news tonight in the chopper crash in Iraq. Seven American service members were killed when their air force helicopter went down near the Syrian border. The U.S. Official says the

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