The bodies of stepsisters Stacy Lemmens, seven, and Nathalie Mahy, 10, were found near a rain water pipe in long weeds alongside a railway track just 200 hundred metres from where they went missing overnight on June 9.
The grisly find brought an end to an 18-day search which saw more than 40 police officers, civilian rescue teams and a helicopter scour the patch of overgrown land between the tracks and a retaining wall.
Police have publicly named just one suspect in the case but they have acknowledged that they have found no evidence linking the man, Abdellah Ait Oud, 38, to the girls' disappearance.
Oud turned himself in to police on June 13, more than three days after the stepsisters disappeared while playing around a bouncy castle near a cafe.
He has denied being involved but has said he was in the area around the time they went missing. He also lives close to where their bodies were found.
Actions 'suspicious'
On Monday, Liege prosecutor, Anne Bourguinont said that his actions had been suspicious.
"The prosecution position is still the same; that he disappeared strangely from his home for three days even though he knew he was being sought by police," she told AFP.
The final results of DNA tests taken on blood and sperm at the man's home are expected to be released this week, although initial findings did not reveal any trace of the girls.
Justice officials said it appeared the girls had been killed some time ago, but Ms Bourguinont, said only an autopsy would be able to establish exactly how and when the children were killed.
The girls' disappearance has rocked Belgium with its disturbing echoes of the Marc Dutroux paedophile crimes, whose case began when two girls went missing in Liege.
In a televised statement, Belgian Prime Minister Guy Verhofstadt sent his condolences to the children's parents.
"The news of this discovery awakens in all of our hearts a feeling of aversion, of sadness and impotence as well. We cannot understand what drives certain people," he said.