Following a three-day operation, which involved the exhumation of a grave at Old Monkland Cemetery in Coatbridge, the detective leading the search, Chief Inspector Kenny MacLeod admitted they had not found the body of the missing schoolgirl.
Moira, who went missing in 1957 while running an errand for her grandmother, is believed to have been abducted and murdered after catching a bus, but no trace of her has ever been found.
But yesterday as police officers and forensics experts shook hands to signal the end of the search of a burial plot at the cemetery, it became clear that Moira's family will continue to face the pain of not knowing what happened to the 11-year-old.
However, officers vowed to continue their work to find her body.
Chief Inspector MacLeod, said: "There is a feeling of disappointment among the officers but the overwhelming feeling is of regret for Moira's family. Suffice to say that the case remains open and we remain committed to finding closure."
On Tuesday, a forensics team, led by Professor Sue Black, began the search of the family plot of Sinclair Upton, an acquaintance of the chief suspect, convicted paedophile Alexander Gartshore.
The Coatbridge bus driver died in 2006 and has long been connected with the case.
The exhumation was ordered after Moira's sister, Janet Hart, who lives in Australia, launched a petition for Mr Upton's grave to be opened in the hope of finding Moira's remains.
It was a painstaking task, however, with a total of eight people known to have been buried in the plot dating back to 1908. A radar survey had suggested there may have been a ninth body there.
But as first revealed in later editions of yesterday's Evening Times, that turned out not to be the case.
The burial plot was being returned to its former state yesterday afternoon, as cemetery staff worked behind plastic screens in the cold and fog.
Gartshore's daughter, Sandra Brown, 63, has investigated Moira's case for decades and has written a book stating her father almost certainly murdered the schoolgirl.
She is convinced Moira's body was somehow hidden beneath the coffin of Sinclair Upton, who died a few weeks after the schoolgirl went missing.
In 1999, convicted child abuser James Gallogley named his former friend Gartshore as Moira's killer.
Sandra said: "While I am very sad about the result and it is not the conclusion I was hoping for, the story of Moira Anderson is still not at an end. This was our best hope and obviously it is not the result we were hoping for but there is still hope there."