Expert witness and pulmonologist Martin Tobin said the defence witness was 'simply wrong' when they stated that George Floyd’s carbon monoxide level could have increased by 10 to 18 per cent.

The comments came during Thursday's second session in the trial of ex-Minneapolis police officer Derek Chauvin.

Tobin was quizzed by both sides on a claim the defence made about George Floyd's carbon monoxide levels.

'In seven minutes Mr. Floyd's carboxyhaemoglobin could have increased by 10 to 18 per cent,' read a statement from defense expert witness Dr. David Fowler.

"It's simply wrong," responded Tobin when asked his opinion on that statement under oath. Tobin went on to explain that the carbon monoxide levels in George Floyd's system were 'very normal.'

The trial of the former officer began on March 29. He has been charged with second-degree murder and manslaughter and third-degree murder after being filmed kneeling on Floyd's neck for nearly nine minutes, leading to his death.

Both sides concluded presenting their cases today while closing arguments expected for Monday.