The sisters were arrested in the stabbing death of their father, Mikhail Khachaturian, in July. Ages 17, 18 and 19 at the time, they alleged he abused them physically and sexually for years. Formal murder charges were filed last week.
The case has revived concerns about tolerance for domestic violence in Russia, which in 2017 decriminalized some violence within families. Assaults that result in bruises or minor bleeding were downgraded to a civil offense punishable by a fine and up to 15 days in jail.
St. Petersburg demonstrator Georgi Romanov says the changes meant the sisters "had no opportunity to defend themselves."