Tina McLeod denies repeatedly shaking the child

Child minder Tina McLeod is accused of murdering Alexander Graham by shaking and twisting him and striking his head against an unknown blunt object or surface.

Neuropathologist Dr Waney Squier told the High Court in Edinburgh that it would be extremely difficult to shake a one-year-old so hard that his head flopped.

Mrs McLeod, 40, denies fatally injuring the toddler in her home in July 2001.

Spinal cord

Alexander died the following day when his parents agreed to his life support system being switched off.

In evidence, Mrs McLeod, of Craigleith Hill Avenue, Edinburgh, vehemently denied violently shaking, slapping or dropping the toddler.

She also told of her panic when she found Alexander on her living room floor.

During her trial doctors and medical experts have blamed violent shaking for his death because of the type of injuries they found in the youngster's brain and spinal chord.

It must have been a very unfortunate and unusual fall Dr Waney Squier

However, Dr Squier, a consultant at Oxford's Radcliffe Infirmary, said she did not accept that theory.

"In order to shake a one-year-old sufficiently to cause his head to flop would be extremely difficult," she told the trial.

Dr Squier said this might happen if the child had been sleeping and there was no opportunity for any reflex reaction.

But she said a toddler of Alexander's age would struggle, go "rigid with fright" and make shaking extremely difficult.

She said that "massive stretching" would be caused if a toddler fell in such a way that the back of his head hit the floor first and his body somersaulted over.

"It must have been a very unfortunate and unusual fall," she said.

When challenged by prosecuting advocate depute, Gerry Hanretty QC, Dr Squier said: "This has been an extraordinary unlucky case in which the body has fallen and stretched the neck.

"I think he must have fallen head first so he possibly stood up on the settee which is a squashy soft sofa.

"He was just learning to walk and he toppled over backwards."

Dr Squier said: "Not all babies topple by falling onto their bottoms. In some cases it does not go according to plan and we have a cevastatingly serious fall.