Friday marks the 10th anniversary of the discovery of the 10-year-olds' burnt bodies near an air base at Mildenhall in Suffolk.
The grisly discovery ended a two-week hunt to find the girls after they disappeared from a family barbecue in Soham, Cambridgeshire.
Ian Huntley, a caretaker at Soham Village College, is serving two life terms for their murder.
His girlfriend, Maxine Carr, a teaching assistant at their school, served 21 months for perverting the course of justice and is now living under a new identity.
Speaking as the anniversary approaches, a criminologist warned that the pain of the killings is likely to “last a lifetime”.
Colleen Moore, principal lecturer in criminology at Anglia Ruskin University, said: “Because of the extreme nature of the crime and because of our fascination with Huntley, it is unlikely that his crime will be forgotten in our lifetime.
“For the wider community there will be a residual sense of grief.
“Even those who did not know the girls or their families will have identified with what they were going through and will have some sense of fear that it could happen again.”
While townsfolk are determined to remember Holly and Jessica, acts of remembrance in Soham are expected to be low-profile.
On August 17 2002, residents flocked to St Andrew's church to await confirmation that the search was over.
The Rev Tim Alban Jones oversaw a special service that night but said there would be no similar service this year.
He added: “It was decided that the church would not be doing anything to mark the 10th anniversary.
“It is very much a time for the families.”
Sharon and Les Chapman, parents of Jessica Chapman, have rarely spoken publicly in recent years.
But they recently broke their silence to hail the first anniversary of the Police National Database - introduced to close gaps in information-sharing between police forces.
The database was the key recommendation from the Bichard Inquiry into failings by police during the Soham murder inquiry after Huntley had faced a series of allegations for rape and under-age sex.
The number of searches carried out by police forces using the database is expected to hit one million in time for the anniversary.
In a statement, Mr and Mrs Chapman said: “We hope [the database's] use will mean other families don't suffer the same loss and heartbreak as we did.”
Holly's brother, Oliver Wells, also recently spoke publicly for the first time about the killings.
Now aged 22, he told the Radio Times that he thought about his sister frequently.
“I wish I could see her now, see what she'd have looked like,” he said.
“We do chat about her quite regularly, which I think is a very nice thing. It's strange being three of us, when there used to be a fourth.”
Her father, Kevin Wells, told an ITV documentary that the stress felt by him and his wife Nicola following their loss almost led to the break-up of their marriage.
But he added: “She was lost in a kind of wilderness whereas I was more hard-line about my emotions.
“For the first five months after Holly died we broke down together, but after that we processed our grief at different speeds.
“It was one, almost two years before we found each other again, but grief gives you a different sense of the passage of time and it slipped by unnoticed.”
He added that the passage of time had not healed the pain but vowed to “make it out the other side”.
Mr Wells ran this year's London Marathon in memory of the girls.
He raised nearly £8,000 for the Grief Encounter Project which helped support his family and of which he is now the patron.
He completed the 26-mile course in five hours, four minutes and 58 seconds.
On his JustGiving website, he wrote that the charity had been vital in helping with “the uninvited grieving process can have on your life and your future”.