Fraudster died in St Thomas’s Hospital after being given flask of acid and drinking it after being sentenced in court

A serial frauster who killed himself by drinking acid in court wasn’t considered a suicide risk by probation staff, despite him having a history of self-harm when stressed, according to an inquest report.

Mark Marshall, also known as Mark Castey, drank the corrosive substance at Inner London Crown Court in Southwark in April 2019.

The career conman, who once tricked the family of disgraced footballer Adam Johnson out of £170,000, had just been sentenced to two years and four months behind bars for fresh fraud offences.

A probation officer said she didn’t believe the 55-year-old would self-harm at the hearing, where he admitted to cheque fraud offences of around £135,000.

But she had noted in a previous report that he was at the greatest risk of suicide when under arrest by police.

Senior coroner, Andrew Harris, said Marshall’s risk of harming himself as he was sentenced wasn’t considered.

In a prevention of future deaths report from December 22, he said: “The evidence suggests that his risks of recurrent impulsive self harm in situations his ex wife described as ‘when he is cornered’ were not fully assessed as applying to the time after he was being sentenced.

“Whether this was due to the policy requiring imminence of risk at the time of assessment or being erroneously interpreted so, or whether the projection of imminence arising in a future context was not fully considered, is not clear.”

Marshall, who suffered from a narcissistic personality disorder, smuggled acid past security and into the courtroom at Inner London Crown Court in April 2019.

He swallowed the noxious substance in the dock in what the senior coroner described as a “meticulously planned suicide”.

Marshall died at St Thomas’ Hospital in Lambeth two months later in June 2019.

He had been assessed by his probation officer six days before his appearance in court.

But the female officer didn’t fill out a suicide risk form about Marshall for court staff, believing he wasn’t at immediate risk of harming himself.

In his report, senior coroner Mr Harris noted: “In court she thought perhaps 50 per cent of offenders have suicidal thoughts, but said only about once a month she filled in a suicide risk notification form.

“She denied she had too high a threshold for assessing imminent risk.

“Her manager did not consider that the length of sentence would be a surprise to the deceased and informed the court that if the threshold for completing a form was lower, it would catch almost all clients.”

Issuing a prevention of future death report, Mr Harris said the public needed reassurance that people with personality disorders would have their risk of self-harm taken into account.

He said: “Whilst the precise circumstances of this death were unique and unpredictable, there is a need for public reassurance that the projected contextual self harm risks of those with personality disorders are recognised and mitigated, especially for those receiving less intensive assessment as they are on bail and not in custody.”