An inmate who regularly chatted with Jeffrey Epstein behind bars has revealed he is convinced the paedophile financier killed himself, after observing his decline.

William ‘Dollar Bill’ Mersey was at the Metropolitan Correctional Center in New York where he had a role as an ‘inmate companion’ while Epstein was on suicide watch.

Mersey spent at least 20 hours chatting with Epstein, especially about how Mersey ended up in jail for tax fraud after under-reporting income from an escort advertising agency.

But he saw Epstein’s downfall first-hand, seeing him in a ‘defeated’ mood and sitting on the floor of his cell eating chicken out of a container between his legs.

Epstein was found dead in his cell at the notorious jail in Manhattan in August 2019 while he awaited trial on sex trafficking charges, with his death ruled as a suicide.

Mersey, who was in the prison between January and November 2019, has now spoken about Epstein in a new BBC Panorama documentary which airs tonight.

He said: ‘I believe he killed himself because I observed him for many, many hours. I observed his decline. Only the last time I watched Jeffrey did his mood really strike me as defeated.

William ‘Dollar Bill’ Mersey was at the Metropolitan Correctional Center in New York in 2019

Jeffrey Epstein was found dead in his cell at the notorious jail in Manhattan in August 2019

‘He was sitting on the floor of his prison cell with a Styrofoam container with chicken between his legs, looking very down and out. And I said: ‘Jeffrey, what are you doing, why are you eating chicken on the floor?’ ‘Oh, it’s just easier this way’.

‘And then he asked me if I needed any money. And I said, ‘well, you know, you’re a billionaire, why would I say no? That’s a ridiculous question’. So he said, ‘Well, I can put some money on your books.’

‘I think in retrospect he was saying goodbye. This is it, I’m going to throw you a few bucks and you’re never going to see me again. I’m going to kill myself at the earliest convenience, which he did.’

Asked whether he ever received the money, Mersey said: ‘No.’

Mersey had signed up as an ‘inmate companion’, which is a programme where prisoners complete four hours of training before taking shifts to observe fellow inmates on suicide watch.

This made him one of the only people who had regular direct contact with Epstein while he was in jail, aside from prison staff and the financier’s lawyers.

Mersey explained how he sat and chatted with Epstein ‘for at least 15 or 20 hours’, adding: ‘I talked a lot about how running an advertising agency for prostitutes worked, which is how I made the money I didn’t declare on my income taxes and ended up there in his company.

‘And he was interested in the business aspect. There were times when he would sort of drift off and I knew he was ‘Oh my God, I was having a good time for a second and now I just remembered the deep s*** I’m in’.’

The cell where Jeffrey Epstein was housed at Manhattan’s Metropolitan Correctional Center

Epstein was in a Special Housing Unit cell at the Metropolitan Correctional Center in New York

Epstein was discovered on the floor of his Special Housing Unit cell, weeks after he was temporarily transferred to the special suicide watch wing of the jail following an earlier suicide attempt.

The US Bureau of Prisons initially called Epstein’s death an ‘apparent suicide’, then the New York medical examiner officially ruled it a suicide.

But that have been various unsubstantiated theories ever since over whether foul play was involved in his death.

Epstein’s accomplice, the British socialite Ghislaine Maxwell, is serving a 20-year prison sentence in the US for luring young girls for him to sexually abuse.

Virginia Giuffre, who died by suicide last year, had accused Andrew Mountbatten-Windsor of sexually assaulting her when she was a teenager after allegedly being trafficked by Epstein. Andrew has strongly denied this.

The King last year stripped his brother of his royal titles after fresh revelations about his Epstein ties and Andrew was forced to leave his Windsor mansion and move to the monarch’s private Sandringham estate in Norfolk.

Andrew and Peter Mandelson, the former UK ambassador to the US, were both arrested in February on suspicion of misconduct in public office over their connections with Epstein.

They were subsequently released under investigation and deny any wrongdoing.

Panorama – ‘Epstein: Money, Power and Abuse’ airs on BBC One at 8pm tonight