A teenager who tried to decapitate his friend was previously expelled from school for threatening a pupil with a knife, it has been reported.
Marcel Grzeszcz, 15, lured Roberts Buncis into woodland before stabbing him more than 70 times in the neck, chest and abdomen.
Two days before his victim's birthday, Grzeszcz had attempted to remove Buncis's hand and decapitate him.
Less than three years before the horrific crime the teenager had been expelled from a primary school for taking a knife into class.
He reportedly used it to threaten a girl at St Nicholas Primary School in Boston, Lincolnshire.
Have you been impacted by this story? Email webnews@mirror.co.uk
Grzeszcz was moved to Haven High Academy but was excluded for selling drugs, The Sun reported.
Grzeszcz was then sent to a pupil referral unit where he started the day before Roberts was found dead.
One mum, who used to take Roberts to primary school with her kids, told the publication: “It’s not his first incident with a knife.
"When he was at primary school he took one into class to threaten other kids. He threatened a girl with it and was excluded.”
Grzeszcz was publicly named for the first time today after a High Court judge ruled doing so was a "necessary public debate on knife crime".
Mr Justice Jeremy Baker permitted the identification of the now 15-year-old after jailing him for the murder of 12-year-old Roberts on Monday.
Grzeszcz admitted manslaughter midway through his trial but denied murder at Lincoln Crown Court
He was sentenced to a minimum of 16 years and 36 days.
The defendant claimed the victim had taken the knife to the scene and he "lost control" when the youngster attempted to stab him, but jurors dismissed his argument and concluded he was "motivated by anger".
Mr Justice Baker said: "Marcel Grzeszcz, in the early hours of Saturday 12 December 2020, you lured Roberts Buncis to a wooded area of Boston where you carried out a savage and brutal attack upon him with a knife which you had brought to the scene, in the course of which you made a determined effort to remove his head, before leaving his body for others to find later that same morning.
"Although it is less easy to discern the precise motive for your actions that night, if indeed they extended beyond the excitement which the infliction of violence had caused you to experience in the past, it would appear that you viewed the deceased as something of a liability.
Following the hearing, Detective Chief Inspector Richard Myszczyszyn of Lincolnshire Police said the case acted as a "stark and chilling lesson on the potential devastation of knife crime".
He said: "The act was utterly senseless and the consequences devastating.
"It will be remembered by officers and staff as one of the worst and saddest cases we have ever dealt with.
"The level of violence, and that it involved children, makes it almost incomprehensible.
"It's a stark and chilling lesson on the potential devastation of knife crime.
"If you, as a parent or a child, have any concerns about knives, please talk to us.
"We can all play a part in building a future free of such desperately sad and unnecessary loss of life.
"We will educate and engage on knife crime and we will continue to relentlessly pursue justice for victims; as we do so, we will remember Roberts."
In a short victim impact statement read to the court on behalf of Roberts's father, Edgars Buncis, he said: "How do I put into words how I feel?
"This is all wrong. No father should ever have to bury their son.
"Nothing is a reason for this. I have lost my destination and my purpose.
"My life is in a cemetery. I feel empty and nothing will change this."
