By Michael Holden

LONDON (Reuters) -A British teenage girl, who had said she wanted to blow up a synagogue and became fixated with Adolf Hitler, had been sucked into far-right extremism by two American neo-Nazis, a British coroner said on Monday.

Rhianan Rudd, who was 16, took her own life in May 2022 at a children's home having been investigated by police and Britain's domestic security service MI5 over extremist views.

Two years earlier, Rudd's mother had referred her daughter to the counter-radicalisation scheme, Prevent.

She is believed to be the youngest girl to be charged with terrorism offences in Britain after she was arrested when 14, though the case against her was later dropped.

At an inquest into her death, the Chief Coroner of England and Wales Alexia Durran said she had been initially radicalised by her mother's former partner, a U.S. neo-Nazi who had convictions for violence.

She was further drawn into extremism by U.S. white supremacist Chris Cook, who was jailed in 2023 for terrorism over plans to attack power grids, Durran also said.

Rudd, who had autism, became obsessed with fascism, even carving a swastika into her forehead, and had downloaded material about making bombs and 3D guns, Durran said.

Durran concluded that both Mallaburn and Cook were each "a significant radicalising influence on Rhianan" who had "played a material role in introducing and encouraging Rhianan's interest in extreme right-wing materials".

LEARNING FROM PAIN

Rudd's mother Emily Carter said she believed that the police and MI5's prolonged investigation had played a role in her daughter's death.

"Whilst nothing can ever bring Rhianan back, I urge all the authorities that came into contact with her to learn from what happened so that no other family has to experience the pain we have endured," Carter said in a statement.

The charges against Rudd were not dropped until August 2021, four months after social workers believed she might have been a victim of sexual exploitation.

However, giving her ruling at Chesterfield Coroners' Court in central England, Durran rejected the argument that the state had played a role in her death, saying it had been appropriate to investigate and prosecute her.

"I am satisfied that the missed opportunities that occurred in this case were not systemic," she said.

British authorities have become very concerned about the online radicalisation of young people. MI5's Director General Ken McCallum said last year that 13% of all those they were investigating were under 18, a threefold increase in the last three years.

Britain's Crown Prosecution Service offered condolences to Rudd's family. "This is a tragic case," added Nick Price, CPS director of legal services. We do not prosecute young or vulnerable people lightly. Terrorism offences are extremely serious, and these are decisions our specialist prosecutors take great care over."

(Reporting by Michael Holden; Editing by Andrew Cawthorne)