Mohammed Abdul-Kadir was punched twice in the face behind flats in Toxteth and fatally cracked his head on the ground when he fell.
The 19-year-old suffered massive brain injuries after the attack in the car park in North Hill Street.
He died three days later in Walton Neurological Centre.
The ECHO has discovered one of his alleged attackers could have confronted Mohammed after suspecting contact between him and his sister.
Hostility may have arisen over Mohamed’s perceived failure to seek permission of the young woman’s family to begin a relationship.
Other theories about the murder surfaced during conversations with people close to the Toxteth Somalian community who suggested Mohammed was coming under pressure from a criminal gang.
Sources told how peers were trying to force him to join their enterprises, asking him to act as a driver for robberies.
Merseyside Police said they were probing different lines of enquiry and keeping an open mind into Mohammed’s death.
A woman pushing her child in a pram found the bleeding Mohammed at 6.45pm on January 26, just off Princes Road.
Detectives have spoken to her, and also to three Somali men who turned up to the scene, as the ambulance arrived, to see the victim.
The 19-year-old had the nickname “Sweden” after growing up in the Scandinavian country.
His family moved to Manchester and he moved to Liverpool in recent months with the hope of beginning to study.
The teenager was only 5ft 5ins and looked a lot younger than his 19 years.
Detective Chief Inspector Kath Adams described him as a much loved son from a family now left devastated.
Officers have checked for CCTV cameras that may have recorded key evidence, and contacted buses on the Princes Road route equipped with cameras.
Police also visited local mosques in the early stages of the enquiry.
They believe the attack was spontaneous and did not involve any degree of planning or premeditation.
A week after the murder, police visited the addresses of suspects, and arrested three men, two of them brothers, aged 22, 22 and 24.
They were questioned, providing no comment in interview, and later released without charge, following advice from the Crown Prosecution Service.
DCI Adams said: "We are determined to bring those responsible for Mohammed's death to justice.
"We continue to explore many lines of enquiry in relation to his death and are keeping an open mind as to the motive for his killing."
Source: Liverpool Echo