Two guns were used in the shooting which killed nine-year-old Olivia Pratt-Korbel in Liverpool, police have said.
Merseyside Police also released CCTV footage of the gunman running from the scene as they appealed once again for people with information to come forward.
Olivia died after she was shot in her home when the gunman chased another man into the property.
A post-mortem examination found her medical cause of death was a gunshot wound to the chest.
Her mother Cheryl was also injured and is still receiving treatment for her injuries, police said.
Detective Chief Superintendent Mark Kameen warned those who are “shielding” the culprit that they “will do everything legitimately possible to bring you to justice”, adding: “It is beyond comprehension how anyone can protect a person who is responsible for killing a nine-year-old little girl.”
In an update on Thursday afternoon, Mr Kameen said the investigation had made “significant progress” and that it was believed the gunman had brought two weapons with him when he “callously ran away from Olivia’s house”.
“I want to know where those guns are now,” he said.
“You may have been told to hide them or dispose of them – I understand you may be frightened of contacting us, but I want you to do the right thing for Olivia and tell us where they are right now.
“If you are hiding the guns and you have no intention of telling us, then I place you in the same category as the vile man responsible for the murder. And we will hunt you too.”
Mr Kameen said the CCTV was being released in the hope that it might job people’s memories about seeing the gunman in the area at the time of the incident on August 22nd.
“This footage shows the gunman running along Finch Lane away from Kingsheath Avenue. You then see him turn right into Berryford Road and go out of sight. We know he is climbing into and through people’s gardens to avoid being seen,” he said.
“As you can see, the gunman was wearing a black padded jacket and a black balaclava with a peak and black gloves, and he is described as approximately 5ft 7in tall with a slim build.
“This is the man we are hunting for – we need to know where he went that night or did you see him in the area?”
He added: “This man is toxic. He is toxic to our communities and if you are protecting him he is toxic to you and your family.”
Mr Kameen said police were also releasing footage of a man who was in the area at the time of the shooting who they wanted to trace.
He said: “I’m interested in speaking to him as he may have information that is important to the inquiry by virtue of the fact he was in the area at the right time.”
A 36-year-old man from Huyton and a 33-year-old from Dovecot were arrested on suspicion of murder and two counts of attempted murder in relation to Olivia’s death last week and have been released on bail.
