A "vulnerable" 18-year-old man who killed himself in a prison cell could have been saved if staff had promptly responded to an emergency alarm, a report has found.
Lithuanian national Osvaldas Pagirys died in hospital on November 14 2016, three days after he was found hanged at HMP Wandsworth, south-west London.
After an emergency cell bell was activated at 1pm, prison staff took 37 minutes to check on Mr Pagirys, despite being aware he had previously tried to harm himself, an investigation by the Prisons and Probation Ombudsman (PPO) found.
A jury returned a conclusion of accidental death on Tuesday following an inquest before Dr Shirley Radcliffe at Westminster Coroner's Court.
Jurors found staff had failed to conduct a "timely" check on Mr Pagirys (pictured) and said the delay in responding to the emergency bell "did contribute to his death".
The PPO report, released following the inquest, found staff had failed to address the inmate's "deteriorating mental health" and had not managed the risk of suicide.
Elizabeth Moody, acting Prisons and Probation Ombudsman, described the death as "deeply troubling", adding: "Mr Pagirys' life might have been saved had staff responded promptly to his cell bell."
Mr Pagirys, who came to the UK in June 2015, was arrested for stealing sweets on July 30 2016 and found to be the subject of a European Arrest Warrant.
He arrived at HMP Wandsworth on August 8, where he displayed "unpredictable" behaviour, fluctuating between trying to harm himself and stating he wanted to live, the PPO report found.
On November 9 he was moved to a segregation unit after racially abusing a staff member and damaging his cell.
He was declared fit to be moved into the ward by a nurse - despite having tried to harm himself earlier that day - in what the PPO report described as a "woefully inadequate" assessment.
Mr Pagirys, who was subject to hourly self-harm checks at the time, was found unconscious in his cell after staff noticed the alarm was sounding at 1.37pm on November 11.
Ms Moody said she was concerned a nurse had assessed an "evidently vulnerable and highly distressed man as fit for segregation".
She added: "The circumstances of Mr Pagirys' death were appalling and tragic.
"He was a vulnerable 18-year-old Lithuanian man who found it hard to cope with prison life and to communicate in English.
"Staff responded to his increasing levels of distress punitively and he was subject to an impoverished, basic regime during much of his time at Wandsworth.
"Staff did not satisfactorily acknowledge his vulnerability or address his rising risk factors.
"Neither the management of his suicide risk, nor action to address his deteriorating mental health, were adequate.
"It is emblematic of the poor care Mr Pagirys received at Wandsworth that it took staff 37 minutes to respond to his cell bell prior to discovering him hanging in his cell."
The PPO report also found Wandsworth had failed to communicate effectively with Mr Pagirys.
Staff at the prison had repeatedly found that the Lithuanian, who struggled with English, was not suffering from mental health problems during assessments without an interpreter, the PPO said.
But when assessed using a translator, a GP agreed to prescribe him with antidepressants and sleeping pills.
In a statement following the verdict, his family described the support Mr Pagirys had received as "inadequate" and said they were "shocked" it took staff so long to respond to the cell bell.
The family said: "We welcome the jury's findings that the prison staff did not carry out timely checks on Osvaldas, that there was a delay in responding to the emergency cell bell and that this did contribute to his death.
"Our hope is that Osvaldas's death has made the management at HMP Wandsworth and the Ministry of Justice pay close attention to the management of those at risk of self harm and ensure that there is adequate supervision of staff."
Rory Stewart, Prisons Minister, speaking after the inquest said: "It is clear there were failings in how he was managed at HMP Wandsworth and these could have been avoided.
"The safety and welfare of people in our custody is my top priority and a significant amount of work has been done at the prison, including improving the monitoring of vulnerable offenders and response times when in-cell alarm bells are triggered.
"The prison has also made improvements that will allow staff to identify more quickly prisoners who require tailored support.
"Prison can be an extremely challenging experience for some and we are determined to reduce deaths and self-harm in our jails.
"Over 11,000 staff have been given new and improved training to help achieve this but we recognise there is much more work to do."
Copyright (c) Press Association Ltd. 2018, All Rights Reserved. Picture (c) GT Stewart Solicitors & Advocated / PA Wire.