Grigory R. Novel about Rasputin

How could an illiterate Siberian peasant be a trustee of the last Russian Empress? Is the case only that he knew how to learn the illness of the heir to the throne? Or was there a different reason for the high confidence rendered by the royal family to this person?
Rasputin was killed in December 1916, and in two months, in February 1917, in Russia, autocracy collapsed. And by decree of the temporary government, a state commission was created to investigate the murder of Rasputin. Investigator Heinrich Svitten interrogated more than one hundred and fifty people passing as witnesses in this case. And that"s surprising: everything, whoever spoke the investigator, everyone converged in one thing that Grigory Rasputin was an outstanding man