By Kevin Bocquet BBC North of England correspondent

Witnessing private grief is awkward at the best of times.

Seeing at first hand the pain of a family who have lost a toddler to an act of brutal violence is almost unbearably moving.

But at the trial of Robert Thompson and Jon Venables, it was the reaction of the other families, the parents of the two accused boys, which provided the starkest memory.

Jon Venables' parents, Neil and Susan, and Robert Thompson's mother, Ann, were sitting a few feet from the jury foreman, when he delivered the verdicts they had been dreading for nine long months.

Father's sobs

It is hard to imagine the depth of sorrow they must have experienced in that moment.

Most of us have in dark moments imagined what it must be to lose a child.

James Bulger was killed on a railway line

But what can it be like to know, to have it confirmed in a court of law, that your child, whom you have fed, cuddled, nurtured and loved, is a murderer?

Neil Venables collapsed, his body convulsed by great shuddering sobs.

His wife sat bolt upright, completely still and expressionless, staring ahead, unseeing.

Around them, journalists rushed to file copy, there was excitement in the public gallery, some of the jury were in tears, and above the commotion, the barristers were continuing their discussions.

Guilty verdict

Mr and Mrs Venables were oblivious to it all, sunk in their agony.

A minute's silence held to mark the anniversary

At one point, Mr Venables placed his hand on his wife's arm, seeking rather than giving comfort.

She did not respond.

He removed his hand, sank his head and continued sobbing.

The trial had ended in slight confusion.

The jury, having delivered verdicts of guilty to abduction and murder, were sent back to their room to continue deliberating on another charge, the attempted abduction of another child.

The two defendants remained in court.

Susan Venables went to stand below the dock.

Her son, red-faced and crying, leant towards her, holding her hand. She was whispering to him.

Bulger's killers were caught on CCTV

What does a mother say to a child killer, who is also her 11-year-old son?

This was what distinguished the Bulger case from other child killings, the fact that the murderers were children.

It aroused in parents deep, unspoken fears.

To the question - Is my child safe? - raised every time a young person is murdered, was added another, darker question - What actions is my child capable of committing?

Angry mob

It explains the vicious, frightening behaviour of the crowd which had gathered nine months earlier at South Sefton magistrates court in Bootle, where the two boys had made their first appearance.

High profile court cases often draw crowds, but the throng which gathered that day was bigger, nastier and more angry than most.

The van carrying the two primary school children, was greeted with a barrage of obscenities, and pelted with missiles.

When it was over, the loudest among them described, for the cameras and the microphones, their great anger at what had happened to James Bulger.

But there was more than just anger in the eyes of that screaming mob.

There was fear.

Fear of the two boys, of other children, of all children, and of their own children.

Fear of what children might do.