The trial of a man accused of being an accomplice in the 2017 suicide bombing at a concert venue in Manchester, United Kingdom has heard he spent months helping to prepare and plan the attack, and should be seen as shouldering equal blame for the 22 people killed.

A large explosive device was detonated in the auditorium of the Manchester Arena venue in May 2017, which killed 22 people and injured hundreds more. Including those who suffered psychological trauma from what they witnessed and experienced at the scene, the court heard the attack had “nearly 1,000 victims”, reports the BBC.

Many of the dead were young adults and children, and their parents, a feature of the audience of fans who were in the process of leaving an Ariana Grande concert that had just concluded at the venue before the attack took place.

Prosecutors state two men were responsible for the attack, Hashem Abedi and his brother Salman Abedi. Salman was killed instantly when his rucksack bag exploded at the Arena, his body being dismembered and partly decapitated by the force of the blast. His brother had already travelled to Libya, was later captured and extradited to Britain to stand trial, which started last month.

The court heard the bomb had taken months of planning and preparation by the brothers, and that both — the deceased Salman and survivor Hashem — should shoulder equal blame for the attack. Hashem would be jailed for murder if convicted in the trial.

The brothers are alleged to have purchased materials, including chemicals to make the explosives and metal screws and nails to surround it to increase to the lethality of the blast with shrapnel. It is also claimed they frequently changed their mobile phone numbers and rented a flat away from their parent’s home to avoid detection.

The prosecutor told the court: “the surviving brother, is just as responsible for the crimes which resulted in so much death, serious injury and damage following the detonation of the bomb on the 22 May 2017 as his brother… The defendant through his conduct encouraged and assisted his brother Salman to carry out the attack.

“The bomb which was detonated was self evidently designed to kill and maim as many people as possible. It was packed with lethal shrapnel and it was detonated in the middle of a crowd in a very public area – the intention to kill and inflict maximum damage.”

Mr Abedi denies all the charges.

Breitbart London reported last week that because the trial was taking place in the Central Criminal Court at the Old Bailey in London, and many of the families of victims who wanted to attend the trial lived in other parts of the country, railway companies were giving them free passes to make travel easier.