On Monday night, Olivia Pratt-Korbel was killed by a masked attacker who chased a man into her house in the city’s Dovecot neighbourhood.
Merseyside Police and Crime Commissioner Emily Spurrell welcomed the news that detectives had been given a lead.
I’m delighted to hear that information is being shared,” she told the BBC.
“It was the plea issued yesterday; we know someone out there knows what happened and who is involved.”
Officers are also conducting house-to-house inquiries and reviewing CCTV footage.
The gunman “fired indiscriminately,” according to police, striking Olivia in the chest as she stood behind her mother, Cheryl Korbel, who was shot in the wrist.
The pursued man was also shot and is in serious but not life-threatening condition in the hospital.
He has not yet been interviewed by detectives, and he has not been arrested.
Mrs Korbel is being treated in another hospital.
According to police, the family had no connection to either of the men.