The nine-year-old was killed when a masked gunman opened fire as he chased a convicted burglar through the door of her home in Kingsheath Avenue, Dovecot, on 22 August.
Investigators are still hunting for those responsible for her death but have now identified the two guns used in the shooting – a .38 revolver that killed Olivia, and a Glock-type self-loading 9mm pistol that has been used in three attacks in Dovecot over a two-and-a-half-year period.
The first incident took place in Wimbourne Close on 27 January 2020, when a 19-year-old man was shot and injured.
One of the bullets went through the front door of a house of an innocent member of the public in a chilling echo of the shooting in which Olivia died.
The second attack was on 8 August 2022, just two weeks before Olivia’s death, and just around the corner from her home.
During that incident two rival groups, one in a car and the other on motorbikes, fired shots “indiscriminately” near playing fields in Finch Way.
Investigators believe the Glock is owned or controlled by an individual or group in Dovecot – and that it could still be hidden in the area.
Detective Chief Superintendent Mark Kameen, of Merseyside Police, said: “Clearly the gunman doesn’t want us to find these guns because it may link him back to them and thereby Olivia’s murder.
“However, and as I have already stated in previous press conferences, this man is utterly toxic to our communities.
“Nobody wants this man around them or where they live. Nobody wants to be associated with him.
“Some people may tolerate him through fear, but even those people, given the choice, would want him locked away. With your support we can make this happen.”
Police released an image of a replica of the Glock and a map showing where the three incidents took place during a press conference at the force’s headquarters in Liverpool on Wednesday.
Nine people have so far been arrested on suspicion of various offences, including murder and assisting an offender, but have since been released under investigation.
DCS Kameen appealed for patience as he insisted the investigation was “progressing well”.
He also revealed the man shot and injured during the shooting on 22 August was still receiving treatment in hospital and that it was not known when he would be released.
Crimestoppers is offering a record £200,000 reward for information to help catch Olivia’s killer.
A £100,000 sum was offered by a private donor, and the charity’s founder Lord Ashcroft has matched that for the biggest single reward offer in its history.
It comes just a week after Lord Ashcroft offered a £50,000 reward through his charity in return for information that leads to the conviction of those responsible for Olivia’s death.