Sandra Brown believes her father, Alexander Gartshore, murdered 11-year-old Moira Anderson and hid her body in Old Monklands Cemetery in 1957.
She was speaking as a police operation continues at the grave where the child's body may be hidden.
Mrs Brown said she hoped the operation would bring closure to Moira's family.
Moira Anderson vanished during a trip to the shops in Coatbridge.
Bus driver Gartshore, a child rapist who died in 2006, has been linked to her disappearance.
Moira's family believe she may have been killed and buried at Old Monklands Cemetery in the family plot of Sinclair Upton, an acquaintance of Gartshore.
Speaking to journalists at the cemetery on Wednesday, Mrs Brown said: "My father was every bit as much of a paedophile as Jimmy Savile ever was.
"My sad conclusion is that Moira is not the only child in the central belt of Scotland who suffered this fate.
"Whether we find her or not, we know we've looked. I hope to see results in the next few days."
Mrs Brown said the exhumation was "very much the end of the road" as she did not know where the investigation could go if Moira's body was not found.
She said it was her belief that there was a "paedophile ring" operating in the area at the time the schoolgirl went missing.
The children's protection campaigner, who was a childhood friend of Moira, said she believed other victims of abuse may have come from care homes, with the cases never being reported.
Mrs Brown said that when she first raised the issue of a paedophile ring in the area in the early 1990s, she was treated with "scorn".
She added: "Given recent events with Mr Savile, people are now realising that this is not a modern phenomenon. It has gone on for a long time."
Mrs Brown, who has received an OBE for services to child protection, set up the Moira Anderson Foundation in 2000 to tackle sexual abuse of young people.
In 2006, she published the book, "Where There is Evil", which outlined her belief that her father had murdered Moira Anderson.
The digging at the Upton family burial plot began on Tuesday under the supervision of Strathclyde Police and is expected to last four days.
A radar imaging scan of the plot in 2007 uncovered inconsistencies in the soil which may indicate the presence of an additional body.
The daughter of a man who is suspected of murdering a schoolgirl 55 years ago says her father was "every bit as much of a paedophile as Jimmy Savile".