The pair were both aged 14 when they murdered Katie and Elizabeth Edwards in Spalding, Lincs. while they slept.
They plotted the killings in a McDonald”s three days before slitting their throats and smothering them with their pillows on April 15.
After the murder, they watched Twilight, had sex and took a bath together.
They join a list of sick baby-faced murderers that have shocked the nation.
James Fairweather stabbed victim James Attfield 102 times in a park while still aged 15, then three months later he knifed student Nahid Almanea as she walked along a nature trail in town.
The 17-year-old was found guilty of murder at Guildford Crown Court earlier this year.
The monster, who acts out how he stabbed victim James Attfield in a chilling police interview video, claimed he was possessed by the devil and idolised the Yorkshire Ripper.
Jon Venables and Robert Thompson
Venables and Thompson became England”s youngest convicted murderers in 1993 when they were sentenced for the killing of two-year-old Jamie Bulger.
The duo, both aged 10, lured the tot away from a Liverpool shopping centre and took him to an area near some railway lines.
They beat him with bricks and an iron bar before stuffing batteries in his mouth and placing him on the tracks.
The pair were released in 2001 when they turned 18. Both of them were given new identities and lifelong protection from having their identities revealed.
Daniel Bartlam was 14 when he beat his mum to death and burned her body.
He initially told police she was killed by an intruder to their home in Redhill, Nottingham, back in 2011.
Then he altered his story, claiming he killed her after losing control in an argument.
But after examining his computer, detectives recovered a deleted story in which a character called Daniel Bartlam killed his mum in the same circumstances.
Nottingham Crown Court heard the teenager had been inspired by a plot in Coronation Street – when character John Stape killed a woman with a hammer.
Bartlam denied murder, claiming he was provoked but the jury found him guilty and Bartlam was sentenced to life with a minimum term of 16 years.
Santre Sanchez Gayle
Santre Sanchez Gayle shot young mum Gulistan Subasi dead – and was paid a fee of £200, which he used to buy a gold Dolce and Gabbana hat.
He was just 15 when he was caught on CCTV shooting 26-year-old Subasi.
The images showed Gayle approaching Subasi on her doorstep, shooting her at point-blank range and casually walking away.
Gayle was a “younger” in a north-west London gang and also known as “Riot”.
He was also a low-level cannabis dealer who expected £2,000 for the crime, rather than the £200 he was paid.
He denied the murder at his trial at the Old Bailey, but was sentenced to life with a minimum term of 20 years.
Police still believe the murder was a hit, but it is still unclear who ordered it.
Sharon Carr was just 12 when she stabbed 18-year-old hairdresser Katie Rackliff 32 times.
Some of the knife thrusts went straight through her body.
The crime went unsolved until Sharon Carr received a two-year prison sentence for stabbing a fellow schoolgirl in Surrey.
When in prison, she admitted the murder.
Police obtained her diaries and found she had written about committing the murder and experiencing sexual pleasure from the killing.
Katie Rackliff was thought to be a completely random victim attacked on her way home from a nightclub.
Carr denied she was responsible for the murder at the trial, but was convicted on the basis of her police interviews and contents of her diary.
In 1999, she was sentenced to a minimum of 14 years but after a review in December 2003, this was lowered to 12 years.
Carr proved to be incredibly difficult to manage while incarcerated and attacked other prisoners and staff on several occasions.
She was sectioned under the Mental Health Act 1983 and assessed as suffering form schizoaffective disorder.
Teenage killer gang
A gang of 20 teenagers aged 15 to 18 murdered schoolboy Sofyen Belamouadden in the ticket hall of Victoria station.
They planned the attack on social media and even sourced a set of knives from Argos during their lunch break.
Then, on 25 March 2010, they chased him down an escalator and pushed him to the floor before hacking and kicking him to death.
The attack was carried out in front of hundreds of commuters and they were armed with knives, metal bars and even a samurai sword.
Sofyen was stabbed nine times and suffered wounds to his heart, lungs and major blood vessels. He was rushed to hospital but could not be saved.
Police trawled through hours of CCTV footage to find the culprits and analysed their communication on Facebook and BlackBerry messenger.
All 20 were charged with murder initially but after several trials over two years three of the teens were convicted.
Ringleaders Samson Odegbune and Christopher Omoregie, who were 16 and Obi Nwokeh, who was 17, were sentenced to a minimum of 18 years behind bars in April 2012.
Five others were convicted of manslaughter including 18-year-old Victoria Oseteku, who sourced the knives and was seen on CCTV kicking Sofyen in the head as he lay dying.
Nine others were convicted of lesser charges and three were cleared.
The total jail time handed out added up to 140 years.
Connor Doran, Simon Evans and Brandon Doran
The Doran brothers and friend Simon were running wild through Liverpool”s streets on the night of August 17, 2012, when they beat homeless Kevin Bennett, 53, who was sleeping outside an Iceland supermarket.
Connor, 17, said to Simon, 14: “I bet you haven”t got it in you to do him in.”
Brandon, 14, kept watch as the pair kicked him to death and climbed on a storage cage to jump on his chest.
He suffered a fractured eye socket, a collapsed lung and a broken ribcage and died from blood poisoning six days later.
“Pack leader” Connor was sentenced to a minimum 12 years in prison, Simon to eight and Brandon to six.
Mum Linda Doran, 42, was jailed for 30 months for perverting justice after providing false alibis, claiming Connor had been six in bed during the murder.
She had told detectives that Connor had been sick in bed at the time of the murder.