An “evil” teenager has been found guilty of the savage murders of two sisters he stabbed to death in a north London park as they celebrated a birthday.

Danyal Hussein, 19, repeatedly stabbed Buckinghamshire Council social worker Bibaa Henry, 46, and her sister Nicole Smallman, 27, after using his own blood to sign a pact with mythical King Lucifuge Rofocale, the Old Bailey heard.

In a “campaign of vengeance” Hussein pledged to kill six women every six months to win the Mega Millions Super Jackpot of £321 million and carry on killing women as long as he was able, jurors heard.

In another sinister note, he offered blood to ‘demon Queen Byleth’ to make a girl at his school fall in love with him.

Hussein’s killing spree was halted because he cut himself during the frenzied attack on the sisters, enabling police to track him through DNA.

A jury found Hussein guilty on Tuesday of two counts of murder and possession of a knife with intent after a jury deliberated for around eight hours.

He stood facing the jury and crossed his arms as the verdicts were delivered in front of the victims’ parents.

Jurors were not told of the extent of Hussein’s obsession with demons, spells and potions.

It can now be reported that he had come to the attention of police aged just 15 over fears he was vulnerable to radicalisation and violent extremism.

Detective Chief Inspector Simon Harding revealed that Hussein had been on a de-radicalisation programme between October 2017 and May 2018 after being referred to the Prevent scheme by his school.

Following his arrest, police found Hussein had communication with others about demons and love potions, and carried out online research about the far-right and Norse mythology.

But the depths of his cult-like ideology remain unknown because Hussein refused to hand over his passwords for his iPad.

Mr Harding described Hussein as “arrogant” and “evil” saying he acted like a “belligerent child” in court.

The senior officer said: “He’s shown complete disrespect to the court system, turning his back on the judge, trying to stare out the family, and laugh, and sticking up loser signs.

“He has behaved like a teenage boy but he has committed some of the most savage crimes we have seen for many years in one of the biggest police investigations we have had for a very, very long time.

“I firmly believe he would have carried out his contract. He would have carried on killing women, until he had killed the first six. If he had not won the lottery by that stage – every six months is what he said.

“He is where he should be and will be for a very long time. Even though he is only 18 he is a very, very dangerous individual.”

Police said they could not rule out a racist element to the selection of Hussein’s victims, even though he just referred to women in his demonic pact.

The trial had heard how Hussein prepared for the killings by buying a set of knives from Asda, a black balaclava on Amazon and signing up to a lottery betting website.

In the early hours of June 6 last year, he stalked his victims as they celebrated Ms Henry’s birthday in Fryent Country Park in Wembley, north London, laughing and dancing with fairy lights.

Hussein took Ms Henry by surprise, stabbing her eight times, before he slashed Ms Smallman 28 times as she bravely fought back, sustaining multiple defensive injuries.

Hussein dragged them by the feet into bushes where they lay undiscovered for 36 hours, their limbs entwined.

During the savage attack, Hussein cut his right hand with the 12cm knife which he dropped in the grass.

He attempted to clear the scene and disposed of the sisters’ mobile phones in a pond before returning to his father’s house in Wembley just after 4pm, without his trousers.

Over the next 10 days, Hussein spent £162.88 on lottery tickets and bets – all without success.

On the evening of June 6, the sisters’ worried loved ones reported them missing but officers were not deployed to the park until the next day.

Before police arrived, Miss Smallman’s frantic boyfriend Adam Stone, who could not believe she would have left their pet bearded dragon unattended, began searching the park with his parents.

He was on the phone to police when he found the bodies at around 12.30pm.

Mr Stone broke down in court as he told how he ran into bushes and fell to his knees before his girlfriend’s body after his father found a knife in the grass nearby.

Officers, who carried out a painstaking search, identified blood stains on the knife, bodies and surrounding scene all linked to the DNA of an unknown male.

The national DNA database failed to identify the sample but on June 30, in a major breakthrough, a DNA familial link was made to Hussein’s father, who had a past caution.

Within an hour and a half, pieces of the puzzle came together with Hussein being identified on CCTV buying knives in Asda and returning home after the murders.

Following his arrest, Hussein, who is Iraqi Muslim decent, told police he had Asperger’s syndrome and trouble with his memory, then refused to answer questions.

Searches of his bedroom at his mother’s house in south-east London uncovered a book of spells, handwritten demon symbols and the two blood pacts.

The defendant disputed all the evidence against him but declined to go into the witness box.

Prosecutor Oliver Glasgow QC suggested that if Hussein was relying on demonic intervention he was to be disappointed as there were no deals to be struck in court.

And if there was a devil, it was “in the detail” of the case against him, Mr Glasgow added.

Two police constables have been charged with misconduct in public office after allegedly sharing pictures of the crime scene on WhatsApp and are due to enter pleas later this month.

Separately, the Independent Office of Police Complaints is investigating over the response to the initial missing persons reports.

Olcay Sapanoglu, from the CPS, said the sisters’ lives were “cruelly cut short in the most horrific of ways”.

She said: “Hussein has shown no remorse throughout these proceedings. He has consistently denied being the person caught on CCTV making his way to and from the park or being the person buying the murder weapon at an Asda supermarket.

“The deaths of Ms Henry and Ms Smallman have devastated their loved ones and left a local community reeling. Our thoughts remain with all those affected.”