An inquest jury said that prison officers should have checked more often on a Fishersgate man who hanged himself in his cell.
And the coroner in the case, Richard Hulett, formally recommended that all prison officers should be given training to make them more aware of mental health problems and suicide risks.
The recommendations came at the end of the inquest into the death of Billy Spiller, 21, of Fishersgate Close, Fishersgate.
The inquest was held at at Buckinghamshire Coroner’s Court, in Beaconsfield.
Spiller was found hanging in his cell at Aylesbury Young Offender Institution on Saturday 5 November 2011.
He had earlier pleaded with staff: “Put me on constant watch. I’m going to kill myself.”
On the day of his death staff became aware that he had a noose in his cell.
And the inquest was told that Spiller had previously tried to hang himself in Aylesbury in January 2010.
A consultant psychiatrist in child and adolescent forensic psychiatry who acted as an expert witness in this case said that Spiller’s risk of committing fatal acts of self harm was exceptionally high.
Dr Peter Misch said that this risk could never be low for Spiller because of his history of prolific and extreme attempts and threats to self harm.
He said: “Suicide in a young offenders institute is everybody’s business. Everybody should have been very worried about Billy.”
During his childhood Spiller had learning difficulties, autism and attention deficit hyperactivity disorder (ADHD) diagnosed.
He self harmed as a child and first used a ligature when he was 16 years old.
Dawn Spiller, Billy Spiller’s mother, said: “I just can’t believe that Billy was left in the care of two prison officers who had no mental health or first aid training.
“I wouldn’t trust them with my cat, let alone young people with mental health needs.
“Throughout Billy’s life I tried to get proper care and support for him but all the doors were shut in my face.
“From the moment he was sentenced to imprisonment, I knew that they wouldn’t be able to look after him.
“They should have diverted him from the courts or made sure that everybody in the prison had training to deal with him.
“It is really important to get rid of the stigma around mental health and to recognise that people like Billy need treatment and not punishment.
“I don’t believe that justice has been done for Billy. We will never give up our fight so that other people do not have to suffer like him.”
Deborah Coles, co-director of Inquest, said: “It is especially shocking that such system failings were identified and staff were not properly trained given what is known about the particular vulnerability of young people in prison.
“Billy Spiller is one of 145 children and young people aged 21 and under to die in prison since 2000, the overwhelming majority self-inflicted.
“This is why an independent inquiry into deaths of children and young people in prison must take place as a matter of urgency.”
Nancy Collins, the solicitor who represented the family, said: “The witnesses accepted that Billy was extremely impulsive.
“The prison officers considered his threat of self harm to be manipulative.
“Accordingly, his threats of self harm were not taken seriously, the real risk not appreciated and inadequate steps taken when he threatened to self harm.
“This is in spite of clear guidance that prisoners’ threats to self harm should not be regarded as manipulative.”