(NECN: Josh Brogadir, Fitchburg, Mass.) - Authorities are still working hard, while trying to sort out the pieces and the timeline regarding the disappearance of a little Fitchburg boy. The question of where he may be and what could have happened to him remain unanswered.
Five year old Jeremiah Oliver, of Fitchburg, was last seen by relatives September 14, but he wasn't reported missing until three months later.
It was this past Friday when his older sister talked to his teacher at Reingold Elementary School. She then alerted authorities to what they now think could be a horrific crime.
"Right now we're treating this as a very serious crime, actually a potential homicide," said Worcester County District Attorney Joe Early.
Jeremiah's mother, 28-year-old Elsa Oliver and her boyfriend, 22-year-old Alberto Sierra, have been arrested in connection with the boy's disappearance from his Kimball Street apartment.
The charges against Sierra, who is not his father, are two counts of assault and battery with a knife and two counts of assault and battery on a child, for allegedly abusing Elsa Oliver and her daughter.
Oliver was arrested on two counts of reckless endangerment of a child and two counts of accessory after the fact of a felony.