Murdered man had been in prison Daniel Keatinge, 25, was found in Formosa Road, Fazakerley, on Friday evening with bullet wounds and was later pronounced dead in hospital.
The victim was jailed for eight years in August 2003 for injuring two clubgoers in Liverpool city centre.
Merseyside Police said the motive for Keatinge's murder was unclear but they did not believe it was gang-related.
However, Keatinge was known to them because of his criminal past when he shot at a nightclub doorman but struck the clubbers. Neither was seriously hurt.
He admitted wounding, possessing a firearm with intent to endanger life and dangerous driving at Liverpool Crown Court.
A post-mortem examination revealed Keatinge has suffered four bullet wounds.
Det Chf Insp David Brunskill, said: "There is nothing to say that his history has anything to do with this incident but we are keeping an open mind.
"I can say there is no evidence to suggest this is gang related."
"This is a very quiet residential area and we are confident we will be able to piece together the movements of the offender."
Police are studying CCTV footage from the area in a bid for clues.
The lone gunman who shot Keatinge escaped on foot in the direction of Eagle Dene via a footpath and then is thought to have gone into Hawkmoor Park.
He is described as 16 to 20 years old and wore dark clothing at the time of the shooting.
Officers want to trace a silver car seen parked on Formosa Road before the shooting.
Keatinge, who was single and unemployed, had been with friends on Friday.
Mr Brunskill said Keatinge's family have been devastated by his death.
He added: "They are clearly very traumatised by the loss of a son.
"We are determined to find the person responsible for the murder of Daniel."
THE BBC