"Initial forensic medical examinations suggest it could be around 2,000 years old," Lutz Gaebel, spokesman for the public prosecutor in Verden, Lower Saxony, told The Local on Wednesday.
"It will be at least another six weeks before we are sure. But should this estimate be confirmed, it will certainly lead to the end of any investigation we conduct into the death," he added.
The boy's father, Lutz Wolfgang Kettler, called authorities after his son found the chest containing the mummy tucked away in a dark corner of the attic.
He later said he could remember his own father having had a chest shipped back from North Africa when travelling there in the 1950s.
Kettler was sceptical at first, saying he thought it was indisputable that the mummy was a replica, but it now seems his son's cry of mummy may have been correct after all.