Safaa Boular, 18, had been trying to reach Syria in order to marry an ISIS fighter, but when her attempt was foiled by police, she turned to plotting a suicide bomb and gun attack on the British Museum.
Her older sister Rizlaine, 22, and her mother Mina Dich pleaded guilty at an earlier hearing to taking over the plot and planning their own attack, after Safaa was arrested by police in April last year.
Prosecutors told the trial that by early 2016, Safaa Boular had developed an extremist mindset, downloading pictures of a child in a suicide belt, a woman in a suicide belt and images of beheadings.
She was interviewed by police in August 2016 as she returned from a family holiday in Morocco and admitted the idea of dying as a martyr “appealed” to her.
She told officers she had 300 or 400 ISIS “friends” online that she kept hidden from her British friends.
The teenager formed a romantic online relationship with Naweed Hussain, originally from Coventry, and more than 15 years her senior.
She planned to travel to the Middle East to marry Hussain, who was fighting for the terror group ISIS in Syria.
The pair spent hours each day chatting online and sharing pictures, some sexually explicit, but many of a violent nature.
The court was shown numerous pictures of Hussain posing with weapons and explosives.
He also shared images of himself attending ISIS executions.
Communications recovered from Boular’s mobile phone showed she had discussed suicide bombing with Hussain on 16 August 2016, when he sent her a picture of himself in a suicide vest.
He told her: “Don’t eva b hesitant 2 pull da pin ok. Ur honour is worth more than any kaafirs [non-believer’s] life. Me n u in jannah [paradise] 2gether. We depart 2 world holdin hands.”
She replied: “Wanna leave dunya [this world] tho. I want jannah so bad.”
After questioning by police, Safaa continued to communicate with Hussain using a secret phone and the encrypted app, Telegram.
Meanwhile MI5 used specially trained role-players to pose as fellow extremists online, in a bid to discover what the pair were planning.
In December 2016, Hussain told one of the MI5 agents that the plan involved someone he “trusted with his life”, adding: “The place that has to be visited is the capital. I believe this is best for maximum carnage. The other person will not go alive, I tell you this now, so all out until you reach jannah [paradise].”
In April last year, MI5 bugged the Boular family home in Vauxhall, south London, and heard Safaa discussing with her mother what it would feel like to die as a martyr.
Duncan Atkinson QC, prosecuting, said there was “nothing conventional” about Safaa Boular’s relationship with Naweed Hussain.
He said Boular “planned to launch an attack against members of the public, selected largely at random, in the environs of that cultural jewel and most popular of tourist attractions, the British Museum, in central London”.
He added: “This would have been an attack that would, at the very least, have caused widespread panic, but was intended to involve the infliction of serious injury and death.
“Whilst Naweed Hussain had undoubtedly done much to encourage Safaa Boular in these plans, the intention underlying those plans was always hers. She was encouraged, but she was willing; she was supported but she was resolute.”
On 4 April, UK authorities were told Naweed Hussain was killed in the fighting in Syria.
In the days that followed, Safaa Boular was arrested and held in a youth detention facility in Kent.
But authorities continued to monitor her communications with her family, as she encouraged them to proceed with the attack plan.
In a phone call with her sister Rizlaine, the pair used coded language, referring to the upcoming attack as an Alice in Wonderland-themed tea party.
Rizlaine told Safaa: “It’s going to be like me and a few sisters and stuff and we’re just going to have fun. It’s basically going to be like a tea party and stuff.”
It can now be disclosed that MI5 bugged the house of Rizlaine’s friend where they heard her rehearsing the attack.
Another bug at the Boular family home had earlier recorded Safaa and her mother laughing about the Westminster attack last March in which five people were killed, including PC Keith Palmer.
Rizlaine and Mina Dich visited a local Sainsbury supermarket in order to buy kitchen knives, which they were planning to use to stab a police officer near Parliament.
The pair also undertook a reconnaissance trip by car, driving around major landmarks in the Westminster area.
Detectives believe the attack was planned to take place the next day, 27 April, the day that Rizlaine and her mother were arrested.
Fearing the attack was imminent, specially trained counter terrorism firearms officers raided a house in Willesden, north London.
Rizlaine Boular was shot and injured by officers as they forced their way into the house. She has since made a full recovery.
The shooting is still under investigation by the Independent Office for Police Conduct.
Deputy Assistant Commissioner Dean Haydon, the UK’s senior national coordinator for counter-terrorism policing, said the mother and daughter terrorist cell were highly dangerous.
“This case started with the youngest daughter, Safaa Boular, who was certainly planning to commit an attack here in London,” he said.
“When she was subsequently arrested the mother and the other daughter then took her place.
“So yes, a really concerning and unusual case that involves a family unit who were intent on committing a terrorist attack.”
The trio’s desire to become Britain’s first all-female terrorist attackers was ultimately foiled by many months of investigation and surveillance by counter terrorism police and the security services.
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Mina Dich and her two daughters are facing the prospect of many years behind bars.
They will be sentenced at a later hearing.