The Russian government is to blame for the poisoning death of Alexander Litivinenko, according to the authors of a new book about the former Russian government critic and KGB agent.

Alex Goldfarb, who was Litivenko's best friend, has written 'Death of A Dissident,' a new book about the life and times of Litivenko with his widow Marina.

Litivinenko -- known as Sasha to his friends and family -- died in November in a London hospital after becoming mysteriously sick with a serious illness. His condition rapidly deteriorated and he eventually died. It was later determined by British investigators that he had been poisoned by the radioactive substance polonium-210.

"From the moment we realized it (was) poisoning, it was kind of automatic that Russia was suspect because Sasha fled Russia in fear of his life in the first place," Goldfarb told CTV's Canada AM.

"So he talked about it from day one of his illness, and actually when I spoke to the doctor first, we said this man is protected by the British government from Russia that's why he got asylum and so it was quite obvious."

Litvinenko dramatically left his post as a senior intelligence agent in Russia in 1998 because he was ordered to execute a prominent Russian businessman. After fleeing to Britain in 2000, he became a vocal and outspoken critic, writing and publishing books and articles critiquing the Russian government and the country's president, Vladimir Putin.

After a series of business meetings in early November 2006, Litvinenko became sick and was admitted to hospital. While he and his wife initially suspected a case of food poisoning, Litivineko suspected something more sinister was afoot.

"When it didn't stop and started to be worse, Sasha said maybe this couldn't be food poisoning, it looks more like chemical poisoning," his widow Marina told Canada AM.

"He used to study in military school, this knowledge. But of course I tried to calm him down to say 'Sasha. Why? Who could have poisoned you?' It could be only maybe food or maybe it's like some flu or anything else because it's scary to think about poisoning of him."

However, Litivinenko's worst fears were confirmed. In a statement read by Goldfarb after his death, Litivinenko claimed that Putin was responsible for his death. The Russian government has vigorously denied the charge.

Despite the fact they support Litivinenko's viewpoints at his death, Goldfarb and his widow are not very concerned about any repurcussions on their own lives.

"I feel (I'm) safe in London, (I'm) protected," Marina Litivinenko said. "I hope it will not happen with me. I don't like to have any special security around me, even for my son, because he deserves (a) normal life."

While Goldfarb also thinks there is no immediate cause for concern, he is wary about the future.

"Because of the special nature of polonium, this was not supposed to be discovered and would have gone as an unexplained death. But now after the scandal broke out, because the polonium (-210) was found, the traces led to Russia," Goldfarb said.

"I don't think in the short run any of us are in immediate danger. But in the long run, it's a very vindictive system and insecure and angry government, so in the long run I think there is some danger."

Last month, British investigators said they believed they had gathered enough information to charge Russian businessman Andrei Lugovoi, a former agent and bodyguard, who met with Litvinenko at the Millennium Hotel in London on November 1 with the former spy's murder.

Russia has refused to extradite Lugovi because it conflicts with the country's constitution.

British Prime Minister Blair discussed the Litivinenko case with Putin at the G8 summit last week; however, no progress was made on the matter.

For the authors of the book, revealing the information surrounding Litivenko's death is the most important issue.

"What is more important for me at least is that people know about what's going on and they can make their own conclusions even from the fact that the Russian government appears to cover up this murder and reasonable people will understand what is going on," Goldfarb said. "That's a form of justice too."