A man has been arrested on suspicion of murdering Olivia Pratt-Korbel.
Merseyside police have a 36-year-old man, from Huyton, in custody.
He has also been arrested on two counts of attempted murder.
The man was arrested by detectives investigating the nine-year-old's murder last night, on Thursday, August 25.
Schoolgirl Olivia was shot dead in her own home, on Kingsheath Avenue, Dovecot, after a gunman burst through her front door.
A spokesperson for Merseyside police said: "We have arrested a 36 year-old man on suspicion of the murder of nine year-old Olivia Pratt-Korbel. The man, who is from the Huyton area, was also arrested on two counts of attempted murder.
"The arrest came after an operation involving armed officers in the Merseyside area last night, Thursday 25th August. The man is currently in custody where he is being questioned by detectives.
"An investigation remains ongoing and anyone with information is asked to DM @MerPolCC or contact @CrimestoppersUK on 0800 555 111. Information, footage or images can also be submitted via the Public Portal (mipp.police.uk)."
The gunman was chasing two other men at the time of the shooting.
One of them was 35-year-old convicted criminal Joseph Nee, who was also injured in the shooting. Detectives believe the attack was linked to organised crime.
Olivia had been behind her mum, Cheryl, at the time of the attack. She was hit in the chest with the same bullet that injured her mum on Monday, August 22. She was rushed to Alder Hey Children's Hospital where she later died.
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