Putin killed Litvinenko
Putin killed Litvinenko (Путин убил Литвиненко) is commonly accepted version of death of Aleksandr Litvinenko. This concept implies that Vladimir Putin orders the assassination, Nikolai Prtushev organises it, and Dmitri Kovtun and Andrei Lugovoi perform it. .
The nuclear reactions in the unstable isotope of Po is used by the KGB agents to kill Litvinenko.
The terroristic act is performed at the territory of the UK, against the citizen of UK in a way, dangerous for other citizen, residents and guests of the UK.
For this reasons, the terroristic act is interpreted as nuclear attack of KGB against the United Kingdom. Several authors expect that nuclear attack on a nuclear country may have serious consequences not only for the terrorists directly involved in the murder, but also for other KGB agents around the world and even against state of Russia, as the main office of KGB ("FSB") is located at Lubyanka, at the territory of Russia, that is formally controlled by the Russian government.
The only one self–consistent explanation of death of Aleksandr Litvinenko is available; it is concept suggested by Sir Robert Owen .
In this sense, the concept by Sir Robert Owen can be considered as Scientific fact.
This concept agrees with more general concept about criminal, terroristic activity of the KGB agents; and also agrees with even more general concept about corruption in Russia of the beginning of century 21, namely, that this corruption got not only large scale, but become the typical, usual phenomenon in the life of Russian officials 
Bill Brouder indicates, that detailed investigation of the vase of murder of Litvinenko and other terroristic acts, organised by the corrupted Russian administration, is important for the safety of the UK. 
Not only Litvinenko
Murder of Aleksandr Litvinenko is not only the case of political repression from side of Vladimir Putin and KGB; a hundred of writers is believed to be killed just for their critical publications about Putin. some of them are described In TORI, see Katyn-2, MH17 and Putin killed Nemtsov.
The will of the UK administration to investigate case of the KGB and, personally, Vladimir Putin, believed to be murderer, is boosted by the Russian invasion into Ukraine, 2014-2016. That invasion, in brutal form, explicitly violates not only bilateral peaceful agreements between Russia and Ukrania of years 1998-1999, but also statements of the Budapest memorandum (1994), signed also by the USA an the UK. Administration of the UK are interested to show, that signature of the heads of their country has some practical sense and meaning. Detail investigation of murder of Litvinenko and jailing of the murders is expected to help to neutralise the most dangerous corruption and de-occupy Crimea and Donbass. The strong actions from the USA and the UK about the case are expected to recover the reputations of these two countries.
2016.01.26, David Cameron suggests that fresh sanctions could be imposed on Russia, after an inquiry concluded Alexander Litvinenko was "deliberately poisoned" in an operation "probably" approved by Vladimir Putin. 
Publications about terroristic activity of the KGB agents are collected in TORI with scientific goals.
Evidences, suggested in the cited literature, should not be considered as justification of a terroristic act against Vladimir Putin, Nikolai Patrushev, Andrei Kugovoi, Dmitrii Kovtun, nor that against their relatives.
- http://ru.espreso.tv/article/2016/01/21/putyn_y_patrushev_verdykt_brytanskogo_suda Виталий Портников. Путин и Патрушев: вердикт британского суда. 21 января, 2016, 14:54
- http://www.theguardian.com/world/2016/jan/21/key-findings-who-killed-alexander-litvinenko-how-and-why Esther Addley and Luke Harding. Thursday 21 January 2016 19.19 GMT Key findings: who killed Alexander Litvinenko, how and why. Inquiry report reveals essential evidence behind conclusion of probable Russian state involvement in former spy’s death. Sir Robert Owen’s report into Alexander Litvinenko’s death runs to 338 pages. Written in clear prose, with the odd moment of dry wit, it is a damning indictment of the Russian president and his state, and of the two, sometimes hapless, poisoners - Dmitry Kovtun and Andrei Lugovoi - who followed its secret orders. ..
- http://www.dailymail.co.uk/news/article-3409405/Inquiry-says-Litvinenko-killed-Putin-s-spies.html 'Putin personally approved my husband's assassination': Fury of Litvinenko's widow as bombshell report blames Russian leader for poisoning - sending relations between London and Moscow back into deep freeze. 10:47 GMT, 21 January 2016.
- https://www.litvinenkoinquiry.org/files/Litvinenko-Inquiry-Report-web-version.pdf Chairman: Sir Robert Owen. The Litvinenko Inquiry. Report into the death of Alexander Litvinenko 2016 January 21.
- 2016.01.21. http://www.theguardian.com/world/2016/jan/21/alexander-litvinenko-was-probably-murdered-on-personal-orders-of-putin Alexander Litvinenko 'probably murdered on personal orders of Putin'. Public inquiry concludes that there is ‘strong probability’ that two Russian agents were ordered to poison former spy on orders of Russian secret service.
- 2016.01.21. http://www.dailymail.co.uk/news/article-3409405/Inquiry-says-Litvinenko-killed-Putin-s-spies.html 'Putin personally approved my husband's assassination': Fury of Litvinenko's widow as bombshell report blames Russian leader for poisoning - sending relations between London and Moscow back into deep freeze. 10:47 GMT, 21 January 2016.
- 2016.01.21. https://www.washingtonpost.com/world/putin-implicated-in-fatal-poisoning-of-former-kgb-spy-at-posh-london-hotel/2016/01/21/2c0c5052-bf92-11e5-98c8-7fab78677d51_story.html Griff Witte and Michael Birnbaum. Putin implicated in fatal poisoning of former KGB officer at London hotel. January 21 at 3:12 PM
- http://www.wsj.com/articles/the-russian-state-of-murder-under-putin-1453419231 David Satter. The Russian State of Murder Under Putin. Let the Litvinenko murder inquiry inspire more investigations of the Kremlin’s ugly tactics. Jan. 21, 2016 6:33 p.m. ET. On Thursday, a British inquiry into the polonium poisoning death of former Russian agent Alexander Litvinenko in 2006 implicated Russian President Vladimir Putin in the murder.
- http://samlib.ru/k/kuznecow_d_j/2009april.shtml Доклад по борьбе с коррупцией в высших эшелонах власти. РАБОЧАЯ ГРУППА ПО БОРЬБЕ С КОРРУПЦИЕЙ В ВЫСШИХ ЭШЕЛОНАХ ВЛАСТИ, Россия, 125057, г. Москва, Ленинградский проспект 75-416, тел./факс +7 499 1586251, Е-mail: firstname.lastname@example.org 20 апреля 2009г. N ВК-15.
- http://www.ekonbez.ru/news/cat/15086 Генерал-майор МВД РФ, известный российский криминолог Владимир Семенович Овчинский, возглавлявший в прошлом российское бюро Интерпола, дал интервью, поражающее откровенностью. Генерал признал, что в России произошло полное сращивание государства с криминалом, а бандиты "окопались" на всех этажах власти. 20.06.2012, 10:37
- http://kremlin.ru/transcripts/1566 Д.Медведев. Вступительное слово на заседании Совета по противодействию коррупции. 30 сентября 2008 года, 16:25 Москва, Кремль. Д.Медведев: Коррупция в нашей стране приобрела не просто масштабный характер, она стала привычным, обыденным явлением, которое характеризует саму жизнь в нашем обществе…
- 2016.01.23. http://www.bbc.com/news/world-europe-35388686 Alexei Navalny: 'Putin is the Tsar of corruption'. 23 January 2016 Last updated at 00:30 GMT.
- http://www.theguardian.com/world/2016/jan/26/litvinenko-report-punish-russia-cameron-bill-browder Bill Browder. There is a way to punish Russia for Litvinenko's murder. So why not act? Tuesday 26 January 2016 10.23 GMT. In an open letter to David Cameron, a former Putin supporter says the failure to hold Moscow responsible puts other lives at risk. Dear David Cameron. // I’m writing on behalf of all British activists who fight for justice against dictators around the world. Your government’s decision to not punish Vladimir Putin and senior members of his regime for the murder of Alexander Litvinenko will put the lives of many UK activists and regular citizens at risk. // Putin and others like him look for weakness wherever they can find it. Putting diplomatic and business relations with Russia above criminal justice and public safety is a sign of weakness that will surely lead to more killings on British soil. ..
- https://www.facebook.com/photo.php?fbid=2079745742247483&set=a.1375733532648711.1073741828.100006362311866 Irina Komleva. 2018 March 8. Власти Великобритании инициировали проверку 14 смертей в стране на предмет «русского следа".
- https://www.facebook.com/photo.php?fbid=350404672006643&set=gm.986527828146943&type=3&theater Alex Khvedrchuk. 2016.12.04 А тем временем в Европе стартовала акция в поддержку президента России!
- http://news.sky.com/story/1626936/litvinenko-killing-uk-to-toughen-up-on-russia Litvinenko Killing: UK To 'Toughen Up' On Russia. The PM vows to handle Moscow with "clear eyes and a cold heart" after an inquiry links Vladimir Putin to a former spy's death. 22:21, UK, Thursday 21 January 2016 David Cameron has suggested fresh sanctions could be imposed on Russia, after an inquiry concluded Alexander Litvinenko was "deliberately poisoned" in an operation "probably" approved by Vladimir Putin.
2016.01.24. http://www.telegraph.co.uk/news/worldnews/vladimir-putin/12115920/Why-is-Vladimir-Putin-not-being-dragged-before-and-international-tribunal-and-put-on-trial.html Simon Heffer. Why is Vladimir Putin not being dragged before and international tribunal and put on trial? 8:01AM GMT 24 Jan 2016.
2017.04.10. https://www.thetimes.co.uk/edition/news/mets-litvinenko-inquiry-foiled-by-russian-tricks-lf86jmg7n Dominic Kennedy, Investigations Editor. Met’s Litvinenko inquiry foiled by Russian tricks. April 10 2017, 12:01am, The Times
2017.04.15. http://www.dailymail.co.uk/news/article-4394024/Police-investigating-Alexander-Litvinenko-poisoned.html Nikki Murfitt. Scotland Yard detectives investigating Alexander Litvinenko's death say they TOO were poisoned by Putin's teapot assassins in an extraordinary attempt to thwart their inquiry. Published: 22:01 BST, 8 April 2017 | Updated: 22:30 BST, 8 April 2017
2017.06.20. https://www.buzzfeed.com/janebradley/scientist-who-helped-connect-litvinenkos-murder-to-the Jane Bradley, Richard Holmes, Tom Warren, Heidi Blake, Alex Campbell. The Man Who Knew Too Much. June 20, 2017, at 2:16 a.m. When police entered the red brick house in Oxfordshire, they found the body of a stocky, bushy-haired scientist sprawled across the kitchen floor. Blood from severe wounds in his neck, arms, and stomach pooled around him. A large kitchen knife lay in his lifeless hand, and a second smaller blade was in the kitchen sink. // The murder detective who attended the scene would tell his inquest that she was shocked to witness injuries that were “so extensive”. Still, the police and coroner declared it a suicide – concluding that Dr Matthew Puncher had somehow managed to stab and slash himself repeatedly with two separate knives before succumbing to his wounds. ..