Detectives say they may have witnessed something “vital” after Ava White, 12, died in Liverpool.
A van driver near the scene of the fatal stabbing of a 12-year-old girl may have witnessed something “vital”, police said.
Ava White was out with friends in Liverpool when she was attacked on Thursday. and died shortly afterwards.
The occupants of a silver Enterprise van spotted in the vicinity are being sought by detectives.
Officers continue to question four boys, aged between 13 and 15, who were arrested on suspicion of murder.
Ava was stabbed shortly after the city’s Christmas lights switch-on at about at 20:40 GMT.
Police said officers found Ava collapsed on the ground with “catastrophic injuries” in Church Alley.
Officers have shared a CCTV image of the van that was in the area at the time, asking for the driver to come forward.
The occupants are in no way suspected of being involved in Ava’s death, said Merseyside Police.
In the city centre, a cordon remains near Church Alley while detectives continue their searches for the murder weapon.
Floral tributes have been left near the scene where Ava was attacked.
Ava, who attended Notre Dame Catholic College in Everton, was taken to Alder Hey Children’s Hospital with critical injuries but died a short time later.
Paying tribute to her, head teacher Peter Duffy said the year eight pupil was “an incredibly popular girl with a fantastic group of friends”.
“My staff are working with students to provide all the support they need at this traumatic time.”
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