The “clinical lead” at a heavily criticised London care home where a vulnerable teenager killed herself has pleaded guilty to failing to cooperate with the inquest into her death.

In what is believed to be the first such prosecution, Duncan Lawrence has been warned by magistrates he could face a prison sentence for the offence of “withholding evidence/documentation in relation to a coroner’s inquest”.

Earlier this year a coroner’s jury found that neglect at the Lancaster Lodge care home in Richmond, south-west London, had descended into “chaos” amid cost-cutting that had contributed to the death of Sophie Bennett, a mentally ill 19-year-old.

The former county-level swimmer, described by her family as “bright, loving and caring”, died in May 2016. Her death came after upheaval instigated by the operating charity, Richmond Psychosocial Foundation International (RPFI), which was advised by the internationally renowned mental health worker Elly Jansen.

Lawrence was said at the inquest to have transformed the regime into “a dictatorship – with 19th-century governance”. He had a non-medical doctorate which might have been bought from Knightsbridge University in Denmark, a “degree mill”, the jury heard.

In May, the assistant coroner John Taylor fined Lawrence £650 for failing to attend the inquest. The coroner also referred the matter to the police and the Crown Prosecution Service, which charged him.

Lawrence, 60, appeared at a hearing before Wimbledon magistrates court on Friday where he admitted he was “100% guilty” but said he had been dealing with illness and the death of his mother at the time.

In a statement read out on his behalf, he said: “By not answering all the coroner’s questions, they may have understood I did not take it seriously. I never lied or had negative intentions.

“Both [my] parents were medically fragile and needed my care and attention. My mother passed away in May 2019, my father in spring 2018.

“I was totally stressed out and did not read and answer all [of the coroner’s] questions which I should have … I made multiple recommendations [at the care home] to try and lessen the [disputes] between the parties.”

Charles Smelton, for the CPS, told the court that Lawrence’s failure to cooperate sufficiently with the inquest was “serious because it strikes at the heart of the important investigative part of the coroner’s process”. He added: “It’s important that everyone complies so that justice can be done.”

Email correspondence between Lawrence and the care home was required for the investigation. A Skype link was even offered to enable Lawrence to testify remotely.

The hearing was adjourned for reports. Lawrence has been ordered to return to court on August 27 to be sentenced.

Deborah Coles, the director of Inquest, the organisation that supported the Bennett family, said: “Inquests play a vital role in scrutinising the circumstances of preventable deaths like Sophie’s. A full and fair hearing enables the coroner to do their job. As such it is essential that those involved in providing care attend and give the necessary evidence.

“We welcome the coroner’s robust response to the failure of Duncan Lawrence to turn up and speak for his actions. This subsequent prosecution is an unprecedented step which we hope will lead to accountability in this case, as well as sending a wider message about the importance of exercising candour and openness following a death.”

Bennett’s father, Ben, said: “The extent of [Lawrence’s] disrespect to us by not taking part in the process is extraordinary. There was evidence we wanted to be included. The whole inquest process was meant to be when you find out the truth of what happened.

“You are supposed to be candid and tell the truth but his actions were very lame and disingenuous.”