HARARE, Zimbabwe — A 4-year-old boy who watched President Mugabe’s supporters murder his mother will be in the audience today when the Zimbabwean president and the opposition leader, Morgan Tsvangirai, sign a power-sharing agreement.

Ashly Chiroto’s father, Emmanuel, is a Movement for Democratic Change councilor who was kidnapped by a mob of Mugabe-supporting thugs at the height of the election violence.

Two gangs arrived at their house in Headcliff, an eastern suburb of the capital, looking for him. Mr. Chiroto was away, so instead they threw petrol bombs into the building and seized his wife and son.

As his wife Abigail, 26, sat in the car with Ashly on her lap, the men broke her hands and slashed her stomach open with a knife. Stuffing her mouth with paper to stifle her screams, they dragged her out of the vehicle and shot her in the head.

Mr. Chiroto, 44, said he wanted his son to see the power-sharing ceremony and would set up a memorial, such as an orphanage or a trust fund, named after his wife.

“When he grows up he will know his mother died but at least there is something in her name,” he said. He would tell the boy of “the madness that we saw where a government that was in power was trying to maintain its position by murdering innocent people.”

“I run short of words,” he said. “Every day I think about it, every single day. It was complete destruction. All my clothes, all that I worked for all my life went up in smoke.”

But Mrs. Chiroto and more than 200 other people killed in the aftermath of the polls in March “didn’t die in vain,” he said. “At least we have got something in our hands right now. The MDC is going to have a say in this government.”

The details of the agreement remain secret, and at the weekend Mr. Mugabe, Mr Tsvangirai, and Arthur Mutambara, the leader of a smaller MDC faction, met to try to settle the distribution of cabinet posts without success.