At first, Kosarev denied his guilt, but soon, after some confrontations with the victims, he confessed. Although he admitted to around 137 rapes, the court could only prove around 40 instances, as many of his victims refused to cooperate with the investigators. In March 1997, the court sentenced him to 15 years' imprisonment, of which 10 he served in a standard prison, and the other 5 in a maximum-security prison.
