Teresa Hand Campbell spoke out in memory of her brother Detective Garda Frank Hand (25), from Brideswell, Co Roscommon, who was murdered by the IRA in a post office raid in Meath in 1984.
The Irish Independent reported yesterday how her brother Michael said his "family's blood" was on the hands of Mr McGuinness, who has admitted to having been a member of the IRA.
Ms Hand Campbell said that anyone under the age of 25 had very little memory of what had happened during the Troubles. She said young people were being misled by Mr McGuinness's "glossy campaign".
"Mr McGuinness may say he presents as a peacemaker and he refers to the Good Friday Agreement. I would challenge him that it's because of the goodwill and the decency of families like mine that the Good Friday Agreement was clinched," she told Shannonside Radio.
Frank Hand was just 25 when he was gunned down while accompanying a cash delivery to a post office in Drumree, Co Meath in August 1984.
Ms Hand Campbell said her parents, who are now both deceased, had been left in "total disarray" by their son's death in the IRA post office raid.
"My mother and father would be visibly upset at any family gathering --that there were six, not seven, at the table," she said.
But she said that her parents had remained silent about their loss because they believed there needed to be peace.
Frank Hand married wife Breda, who was also a garda, just five weeks before he was murdered.
"She discovered two weeks after his burial that she was pregnant. Frank never met his daughter. They had a lovely life ahead of them and suddenly it was stolen, it was cut short," Ms Hand Campbell said.
Three men were jailed for the murder of Frank Hand, but later released under the terms of the Good Friday Agreement. The Hand family opposed the early releases and believed that the man who fired the bullet which killed Frank Hand was never caught.
Mr McGuinness released a statement this week in which he said: "As a republican leader I have never and would never stand over attacks on the gardai or the Defence Forces."
A spokeswoman for Mr McGuinness has said he has nothing to add to that.