Donald Trump pumps his fist after hours of testimony: His loyal former staff line up to dump on Michael Cohen in court even as their evidence builds prosecution case

Donald Trump's relief was clear as Monday's first witness left the court. 

For three hours the former president's head bobbed left and right, soaking up the dense financial details of former Trump Organization controller Jeff McConney's testimony.

Then it was over.

Trump pumped his first twice as the bearded, bear-like frame of McConney made his way from the stand. For his part, the former Trump Organization employee nodded at Eric Trump, sitting in the front row of the court, and let out a long, slow breath.

Trump insiders saw it as a good morning.

A relatively low-level figure had delivered a dull tour of invoices, accounting software and months and months of emails, while building up the role of Michael Cohen, the former-fixer-turned turncoat, as a lone wolf before trashing him.

Confessions of a porn star this was not.

Yet it marked the heart of the case against the former and possibly future president, who denies 34 counts of fiddling business documents to hide hush money payments before the 2016 election.

And the jury listened intently to key discussions of 1099 tax forms, ledger entries and message chains. 

At times their heads snapped left to listen to prosecutor Matthew Colangelo's questions then swiveled right to hear McConney's answers, as if they were watching a championship tennis rally not a legal ding dong.

McConney, with his curtains of white hair falling on either side of his face, played the role of Trump loyalist forced to testify by a subpoena.

He made clear he had lost none of his affection for his former boss and at times dished dirt on Cohen, the once loyal fixer who set up the hush money payments at the heart of this trial before turning on Trump.

He was asked what Cohen did for the Trump Organization.

'Uh, he said he was a lawyer,' McConney answered pointedly, triggering the first giggles from the public gallery.

Cohen could be the prosecution's biggest asset and biggest risk. He has admitted his role in paying $130,000 to Stephanie Clifford, better known as Stormy Daniels, for her silence ahead of the 2016 election.

But he has been barred from practising as a lawyer and imprisoned after pleading guilty to campaign finance charges and lying to Congress, among other crimes. 

He has changed his story on the payments. At first he issued stringent denials before they became strident accusations that Trump was guilty.

At some point he will take the stand and the jury will have to make up their minds whether to believe him. 

Last week it was Hope Hicks, a Trump world insider for six years, who made clear her disdain.

She described how Trump once told her that Cohen had made the payment 'out of the kindness of his heart' to silence a false allegation about an affair.

'I would say that would be out of character for Michael,' she said. 'I didn’t know Michael to be an especially charitable person or selfless person.

The public gallery sounded with laughter and she added that she knew him as 'the kind of person who seeks credit.'

It must have been music to Trump's soul. He has been fined repeatedly for slating Cohen and breaking a gag order.

Another Trump Organization employee, Deborah Tarasoff, even tapped Eric Trump's knee as she made her way to witness stand later in the day, in another sign of staff loyalty to the family. 

Monday began with Judge Juan Merchan threatening him with jail if he did it again after finding him guilty of a tenth breach, this time after he claimed the jury was filled with Democrats. 

'It appears that the 1,000 dollar fines are not serving as a deterrent. Therefore going forward, this court will have to consider a jail sanction,' he said. 

Once evidence resumed, the huge figure of McConney took the stand.

He described his 36 years working for Trump, before retiring last year, in warm terms.

He chuckled at an early memory of how he once dropped off weekly cash balance reports on Trump's desk, only for his boss to briefly break off a phone call to tell him he was fired.

Once the call was over, Trump told him he was not fired but he didn't want any more reports showing his cash reserves were down. Next time, negotiate the invoices, was the message. 

'It was a teaching moment. Just because somebody is asking for money negotiate with them, talk to them,' said McConney.

Eric Trump, sitting in the front row behind his father, nodded along at the lesson.

At the same time as professing his admiration, McConney's evidence could provide a roadmap to the rest of the prosecution.

He described learning for the first time about the need to reimburse Cohen when Trump Organisation finance chief Allen Weisselberg talked him through the plan.

'He kind of threw the pad at me and said, "Take this down,"' he said.

Those seven-year-old 'chicken-scratch,' as he called them, were published on the big courtroom video screens, showing how Weisselberg told him the Cohen should be reimbursed $180,000, doubled to account for taxes, with a $60,000 bonus.

The notes show the total was to be divided by 12, giving a year of monthly $35,000 payments.

Later in the day, the checks were shown to the jury, the next step in what prosecutors allege was a corporate records cover-up of transactions to protect the then Republican contender's presidential run.

Or, according to the defense, just a routine check paid to a lawyer for legal services rendered, all booked by low-ranking employees while Trump sat at the White House 300 miles away from Trump Tower.