At the heart of the case is a lawmaker from the ruling BJP, Kuldeep Singh Sengar, who has been accused of rape by the teen. His brother Atul Singh has been accused of thrashing the girl's father, who died in custody on Monday.
Mr Gandhi cited the case to target PM Modi over the fast he plans to hold tomorrow along with his ministers over the recent, wasted parliament session.
The Hindi tweet roughly translates to: "The atrocities committed on a father who was calling for justice for his daughter in Uttar Pradesh has shamed mankind. It is to be hoped that the Prime Minister will hold a fast soon over the violence against women, the failure of law and order and growing anarchy under the BJP rule".
Addressing the media, party spokesperson Randeep Singh Surjewala said: "The Unnao rape victim cried for justice and pleaded with Yogi Adityanath for eight-nine months. However, the Yogi government did not budge because the MLA was protected by him."
"Beti Bachao Beti Padhao" (save the girl child, educate her) -- a campaign close to PM Modi's heart -- should be renamed "BJP se beti bachao" (Save girls from BJP), the Congress leader added.
The 16-year-old -- whose family has been running from pillar to post for justice since June last year -- tried to commit suicide outside Yogi Adityanath's home on Sunday. The next day, her father died at a local hospital, where he was admitted hours before with severe stomach pains.
The 55-year-old was arrested last week on a complaint by his attackers. A video from the hospital, where he underwent a routine medical check-up before being sent to jail, shows him naming Atul Singh as his attacker. At the time, his face bore multiple bruise and lacerations.
The postmortem report said the man had died due to blood poisoning from a perforated intestine. It also listed 14 bruises all over his body. Today, the Allahabad High Court intervened in the issue, asking that the body of the girl's father be preserved if it has not already been cremated. The cremation was held last evening.
Atul Singh was arrested yesterday over the assault. He has been remanded in judicial custody for a fortnight.
Kuldeep Sengar's wife met the UP police chief today, demanding justice for her husband, who she claimed, was facing a media trial.