The High Court in London on Tuesday began hearing evidence from two leading experts in the field of psychiatry to determine the level of suicide risk faced by Nirav Modi if he is extradited to India to face charges of fraud and money laundering, amounting to an estimated USD 2 billion in the Punjab National Bank (PNB) loan scam case.

Lord Justice Jeremy Stuart-Smith and Justice Robert Jay heard from Andrew Forrester, Professor of Forensic Psychiatry at Cardiff University, and Seena Fazel, Professor of Forensic Psychiatry at Oxford University, in the final stages of the extradition appeal being pursued by the 51-year-old diamond merchant.

The two psychiatrists weighed up Nirav's level of depression, which could pose a substantial or elevated risk of suicide. Both revealed conducting personal assessments of Nirav Modi at Wandsworth prison in south-west London, where he has been lodged for over three years, and reported he "only thinks of cutting or hanging if extradited".

The court also heard that depression is classified as a sense of "hopelessness, worthlessness and pointlessness" and that Nirav is currently on prescribed antidepressants, or selective serotonin reuptake inhibitors (SSRIs), of medium grade. His family history of suicide, related to his mother's suicide, was also referred to as a factor.

He sees the world in a bleak way because of his depression, said Forrester, as he told the court that in his diagnosis Nirav Modi suffers from a recurrent depressive disorder of moderate severity and poses a high risk of suicide.

However, Fazel's analysis was that he appeared to be mildly depressed, which is assessed on the basis of certain set criteria such as sustained period of low mood and fatigability, or becoming tired very easily.

He functions reasonably well, responds to questions intelligibly and did not present some of the other criteria for severe depression such as losing sleep, appetite or delusions, said Fazel.

The two experts also disagreed over certain unalterables in Nirav's mental health as Fazel pointed to depression as "treatable illness" would mean his condition could improve if he found the conditions at Arthur Road jail in Mumbai, where he is to be held during trial in India, not as extreme as feared.

The case is listed for a three-day hearing this week, at the conclusion of which the two-judge panel is expected to hand down their judgment over whether there are mental health and human rights grounds preventing Nirav Modi's extradition to India.

Helen Malcolm QC, appearing for the Crown Prosecution Service (CPS) on behalf of the Indian authorities, laid out the detailed assurances given in the case, which cover regular monitoring, medical care, weekly family visits, daily lawyer visits as well as removing ligature points from the prison that could be used for hanging.

It would be a fair comment that there is an element that you would never be satisfied [with the government of India's assurances], Malcolm said.

Edward Fitzgerald QC, arguing on behalf of Nirav, argued that both experts agreed that there was no robust clinical plan in place in India and a comprehensive individual care plan should be agreed ahead of the extradition.

The judges have indicated that the case has now progressed beyond the stage of asking for any further assurances from the Indian authorities and a judgment is likely at the end of the week.

If Nirav wins this appeal hearing in the High Court, he cannot be extradited unless the Indian government is successful in getting permission to appeal at the Supreme Court on a point of law of public importance. On the flip side, if he loses this appeal hearing, Nirav can approach the Supreme Court on a point of law of public importance, to be applied for to the Supreme Court against the High Court's decision within 14 days of a High Court verdict.

However, this involves a high threshold as appeals to the Supreme Court can only be made if the High Court has certified that the case involves a point of law of general public importance.

Finally, after all avenues in the UK courts are exhausted, the diamantaire could still seek a so-called Rule 39 injunction from the European Court of Human Rights (ECHR).

The High Court hearings follow a ruling in August last year by High Court Justice Martin Chamberlain that arguments concerning the jeweller's severe depression and high risk of suicide were arguable at a full appeal hearing. Nirav's high risk of suicide and the adequacy of any measures capable of preventing successful suicide attempts in Arthur Road prison were deemed as the focal points for the appeal.

The permission to appeal was denied on all other grounds, including the admissibility of evidence provided by the Enforcement Directorate (ED) and the Central Bureau of Investigation (CBI) and Patel's extradition sign off. The High Court also noted that the District Judge's approach in ordering extradition in February last year on a prima facie case in the PNB fraud case was correct .

Nirav is the subject of two sets of criminal proceedings, with the CBI case relating to a large-scale fraud upon PNB through the fraudulent obtaining of letters of undertaking (LoUs) or loan agreements, and the ED case relating to the laundering of the proceeds of that fraud. He also faces two additional charges of "causing the disappearance of evidence" and intimidating witnesses or criminal intimidation to cause death , which were added to the CBI case.