The sentence handed down by the North Caucasus District Military Court shall remain unchanged. The appeals have been dismissed.
The Russian Supreme Court thus found no grounds to abolish the sentence.
In accordance with the law, the sentence handed down to Hryb entered into effect on July 23 and became binding.
The North Caucasus District Military Court in Rostov-on-Don sentenced Hryb to six-year imprisonment on March 22. He was found guilty under the Russian Criminal Code article on abetting terrorist activities.
In its appeal, the defense team requested that the sentence be abolished, pointing out that Hryb had been illegally detained in Belarus and brought to Russia. In addition, according to a lawyer, the law enforcement agencies had obtained the testimony Hryb initially provided and which was used as the basis of his sentence under the threat of violence.
Hryb said in court that he denies any wrongdoing and does not understand why he was convicted.
According to the investigators and the court, Hryb, while in Ukraine, exchanged online messages with a female high school student from Sochi from March to May 2017 to persuade her to plant a previously manufactured improvised explosive device and set it off at a prom on June 30, 2017. He recommended that she leave Russia after committing the attack.
Hryb was detained while visiting Belarus on August 24, 2017. It later emerged that he was held at a pretrial detention facility in Russia's Krasnodar.