Detectives investigating the murder of teenage Army cadet Joseph Lappin this afternoon arrested a 16-year-old boy on suspicion of murder.
Joseph, 16, was stabbed in the heart outside a youth club in Everton on Monday night.
Two suspects were arrested and released on bail but this afternoon a Merseyside Police spokesman announced a 16-year-old from Kirkdale was in custody over the killing.
Joseph and two friends were attacked by a gang of up to 15 youths outside the Shrewsbury House Youth Club where he had watched a friend's band.
The trio were attacked by the mob - who were aged between 14 and 20 - but managed to get back into the club.
But it was too late.
Joseph, of Old Swan, Liverpool, suffered a single stab wound which killed him on the steps of the building.
One of his friends was stabbed twice and was described by police as being incredibly lucky to be alive.
The third victim, aged 17, sustained minor injuries.
Senior investigating officer Detective Superintendent Steve Naylor said: "We know that two people played a key role in the attack on Joseph and his friends.
"One of those two was the person responsible for both stabbings."
Yesterday, Joseph's parents, John and Toni Lappin, pleaded with the parents of the killers to speak to the police.