A promise by US legal officials about the future treatment of an alleged American paedophile should not be trusted, an extradition hearing in London has been told.
Former choirmaster Roger Giese is fighting a renewed bid to extradite him from the UK to the US where he is wanted for trial in California charged with sexually abusing a boy under the age of 14 from 1998 until 2002.
The removal of Giese, 42, was previously blocked by High Court judges in London on human rights grounds.
Giese, who has been living in a village in Hampshire under a different name and working for a PR company, sat quietly during as two expert witnesses on US legal proceedings and prison conditions gave evidence via videolink to a hearing at Westminster Magistrates Court.
UK judges had refused to extradite Giese after concerns were raised that, if convicted, he might be subjected to an order for civil commitment - a form of indeterminate confinement in a secure facility.
The judges ruled there was a real risk and such an order could breach his human rights. They also ruled an assurance offered by the US government that this would not happen was "not sufficient".
There is a new assurance from the Orange County District Attorney's office stating that a civil commitment order would not be sought.
Giese is wanted in Orange County, California, on "19 serious charges of sexual offences" against a young boy.
Jeffrey Lowry, a deputy public defender in San Bernardino County in California, estimated that Giese could be jailed for about 20 years if convicted of all offences and might have to serve around 85% of that sentence.
Arguing that the current assurance could not be relied upon Julian Knowles QC, representing Mr Giese, asked: "There is California case law to the effect that the assurance of one District Attorney does not bind on a subsequent District Attorney?"
Mr Lowry replied: "Correct."
Asked if a future District Attorney would feel "bound" by an undertaking made by a predecessor maybe 20 years earlier, Mr Lowry said: "I do not have a crystal ball but no.
"They are not going to know that or consider that."
Richard Subia, who was a warden of a prison in charge of the welfare of 3,500 inmates, told the court that he felt that a convicted sex offender would be at risk of violence in the California prison system.
He suggested that the risk of a serious offence, the possibility of assault or an incident occurring is "very high".
He said: "Every person is at high risk but sex offenders are at a higher risk due to the views of the staff and the people they are incarcerated with."
An extradition request from the United States was first certified by the Home Office in May 2014 and a series of legal battles has been fought over Giese's removal ever since.
He is alleged to have befriended the boy in 1998, when he was working as a voice coach for the All-American Boys Chorus.
Giese has been on the run from the FBI since 2007.
According to a Mirror newspaper investigation, he set up home with a new partner in the Hampshire countryside. There was no suggestion she knew about his past.
Together, the pair built a PR company with clients including travel giant Thomas Cook.
The Mirror reported that, through his company, Giese was invited to join Thomas Cook's digital advisory board and spent more than a year as the firm's "global head of social media".
The hearing was adjourned until tomorrow at 10am.