The incident took place earlier this year in the Chelyabinsk Region town of Bakal and involved two girls and a boy. The 15-year-old boy has already been sentenced to seven years in a juvenile correction facility.
It was established during the investigation that the teenagers had gathered to drink spirits in a flat belonging to one Vladimir Lemitti.
"During their drinking session, the owner of the flat called his 15-year-old guest 'molodyets'. In modern youth circles that is for some reason considered a degrading term," the Gazeta daily quoted an official from the prosecutor's office as saying.
The Russian word 'molodyets' can be translated in various ways, including 'fine fellow' or 'well done', depending on the context.
In response to the "insult" the boy punched and kicked Lemitti, and then grabbed a knife and proceeded to stab him at least 10 times in the chest and arm. Lemitti died of his injuries on the spot.
The two girls present then also picked up knives and cut open the body. They later explained that they had done this to "have a look at his internal organs."
The girls are to be examined by court psychiatrists to determine if they are mentally fit to stand trial.