A record £200,000 reward is being offered for information leading to the conviction of those responsible for the murder of Olivia Pratt-Korbel.
It follows a £100,000 sum offered by a private donor, which Crimestoppers founder Lord Ashcroft has matched, creating the biggest single reward offer in its history.
Lord Ashcroft said: "This case has been incredibly shocking, not just for those who are directly affected, but also for Liverpool and the nation as a whole.
“I am delighted that with the support of a private donor, Crimestoppers can now offer a record £200,000 for information to catch Olivia’s killer."
The nine-year-old schoolgirl was fatally shot in the chest in her home in Dovecot, Liverpool, on Monday, 22 August.
Her mother, Cheryl Korbel, 46, was injured as the gunman chased convicted burglar Joseph Nee into their home at about 10pm.
Merseyside Police have arrested nine men in connection with the murder investigation but all have since been bailed.
Chief executive of the independent charity Mark Hallas, said: “If you’re too scared to speak to the police, please remember that our charity, Crimestoppers, is here to help you do the right thing. Tell Crimestoppers what you know whilst staying completely anonymous.
"Please understand: Crimestoppers has kept its promise to protect your identity since we started back in the late 1980s."
He continued to say: “You can contact us via our website or call our UK Contact Centre on 0800 555 111. Details about how to claim this reward are available online (www.crimestoppers-uk.org).
“When you contact Crimestoppers we never ask for or store personal details.
"All we ask is that you tell us what you know about who killed Olivia so that there can be some slow healing for her mother, her family, the city of Liverpool and everyone who has been touched by this truly awful murder.”
Olivia's mother, Cheryl, bid farewell to her nine-year-old daughter last week, as hundreds gathered wearing 'a splash of pink' for her funeral.
"She was so small yet even as a newborn she had her own mind," she said at the service, which took place at St Margaret Mary's Church in Knotty Ash, Liverpool.
Cheryle described Olivia as "chatty" and "bubbly", and she joked that her daughter would talk so much that they thought she ran on Duracell batteries.
She added: "Olivia knew exactly how to wrap people around her little finger to get what she wanted, especially her brother Ryan and sister Chloe.
"She would often give them a cheeky smile and they would give in instantly."
Ms Korbel ended her eulogy with: "Liv touched so many people's hearts and was loved and adored by everyone.
"She will never be forgotten. I will never say goodbye but what I will say is goodnight, love you, see you in the morning."
More to follow.