Since the Empress had become so dependent on Rasputin, Prince Felix Yussupov and other members of the family believed murder was the only way to get rid of the monk.
On December 16, 1916 (or, per the Gregorian calendar, December 29th), Yussupov invited Rasputin to his home in St. Petersburg. Feeding him cyanide-laced wine and cakes, Yussupov thought killing Rasputin would be easy. He was wrong. Rasputin collapsed from the poison, but did not die.
Later, the alleged details of the murder came out. Yussupov shot Rasputin in the chest, but still he did not die. One of the conspirators shot him twice as Rasputin tried to flee. The shots disabled the monk but, legend has it, he was still alive as conspirators - standing at the top of the bridge at Petrovsky Island - threw his body into the Neva River. His remains were found days later.
Some investigators, however, believe that recent revelations from Russian Archives paint a different picture of Rasputin's death. Using forensic evidence, including information from his autopsy and other investigative materials, researchers have concluded he apparently wasn't as hard to kill as the story his alleged murderers told at the time.
Rasputin made an eerie prediction before he died.
If I am killed by common assassins and especially by my brothers the Russian peasants, you, Tsar of Russia, have nothing to fear for your children, they will reign for hundreds of years in Russia.
...if it was your relations who have wrought my death, then no one in your family, that is to say, none of your children or relations will remain alive for two years. They will be killed by the Russian people...
I shall be killed. I am no longer among the living. Pray, pray, be strong, think of your blessed family.
Three months after Rasputin's death - allegedly by the hand of Romanov "relations" - Nicholas was deposed as Tsar (March, 1917). Less than two years later, the rest of the "mad monk's" prediction came true as well.