Scott Pritchard's murder sparked one of the biggest police investigations seen in Sunderland.
The 19-year-old was bludgeoned to death outside his Hendon home on January 7, 2004.
Last Thursday, Karen Tunmore, 36, from Towton, Killingworth, was charged with his murder after new information had come to light.
She appeared before magistrates sitting at Newcastle Crown Court on Saturday morning and was remanded in custody.
But on Tuesday during a bail hearing she entered a guilty plea to murder and will now be sentenced by a judge at Newcastle Crown Court on October 1.
Her admission ends a 14-year search for Scott's killer after he was found fatally injured outside his home in Lyndsay Close.
He was rushed to hospital with serious head injuries but doctors were unable to save him. The youth, who was on crutches at the time, had been bludgeoned to death.
Despite one of the biggest police hunts in Sunderland’s history, his murder remained unsolved.
Huge resources were ploughed into finding the killer – with investigating officers taking more than 1,300 statements, conducting 115 interviews and collecting 2,141 exhibits.
Extensive inquiries, including a search of Mowbray Park lake, failed to find the murder weapon.
A post-mortem examination concluded Scott - who at the time lived with his mum Kathleen, brother Brett and sister Melanie - had died from injuries caused by a blunt instrument.
An investigation was launched to trace the person responsible for the Scott’s murder but nobody was convicted at the time.
His dad Fred Stacey, who always denied killing his son, was cleared after the Crown Prosecution Service decided there was no realistic prospect of a conviction and offered no evidence against him.
Mr Stacey, then 52, was cleared at a pre-trial hearing at Newcastle Crown Court in October 2005, having previously been charged with murder.
At the time, a CPS spokesman said: "Every case must meet the evidential test set out in the Code for Crown Prosecutors and review of the evidence is a continuing process throughout the life of a case.
"We have reviewed the evidence in this case very carefully and have concluded that it does not meet the evidential test.
"The reasons for our decision have been fully discussed with Northumbria Police and we have written to Scott’s family to offer a meeting so that we can explain it to them."
After he was cleared, his lawyer Nigel Barnes, from Ben Hoare Bell solicitors, said Mr Stacey had been devasated by Scott’s death and was confident he would have been found not guilty had the case come to trial.
Mr Barnes added: "He is grateful to the CPS and the police for the fair and considered decision they have now made and hopes they will reopen the case with a view to identifying the real culprit."
In January 2005, Scott’s step-sister Deborah Stacey, then 33, made an emotional appeal on the first annivesary of his death for people to help bring his killer to justice.
She said at the time: “None of us are ever going to be able to rest until the person who did this is finally caught.”
The Echo offered a £1,500 reward in a bid to find Scott’s killer a month after his death
At the time, the Echo urged local businesses to support the search by putting up similar rewards, in the hope it would help detectives crack the case.
Rob Lawson, Echo editor at the time, said: “It is important Scott’s killer is brought to justice.
“Someone somewhere knows who committed this horrible crime. Please contact the police and tell them who is responsible.”
Detective Superintendent Ian Sharp, who was leading the manhunt, added: “We thank the Echo for their help in trying to find the person or people responsible for this terrible crime.
“This reward has been offered for any information which could lead to the successful conviction of those responsible.”
Last night Scott’s family did not wish to talk about the latest development after being contacted by the Echo.
Speaking on the ninth anniversary of Scott’s death, in 2013, his mum Kathleen said: "There are people out there who know what happened to Scott, but haven’t spoken up.
"They’re nothing but cowards."
Kathleen refused to move from the home she shared with her son, despite the tragic memories that haunt her every day.
She said: "I couldn’t move from here.
"I need to live here because I feel closer to him in this place, but one thing is for sure, I won’t rest until I get justice.
"Somebody out there knows what and why this happened.
"Somebody out there has the information that is going to make a difference."