Investigators on Friday found what they believe to be the remains of a 5-year-old New Hampshire boy in a Massachusetts state park.

The remains were found by a cadaver dog in a shallow grave at Ames Nowell State Park in Abington, WMUR reported.

According to the Massachusetts attorney general’s office, the chief medical examiner will conduct an autopsy on Sunday.

Elijah Lewis was first reported missing on October 14, when police said they believed he hadn’t been seen in six months, as CrimeOnline previously reported. But further investigation narrowed the timeframe, and New Hampshire Assistant Attorney General Susan Morrell told said Thursday the boy was last seen on September 1.

Earlier this week, Elijah’s mother and her boyfriend were arrested in New York. Danielle Dauphinais, 35, and Joseph Stapf, 30, have pleaded not guilty to charges of child endangerment and witness tampering.

Morrell said after the remains were discovered that investigators were saddened about “the fact that he was disposed of down here in the woods.”

“Our sympathies go out to his family and friends of the family and to the community who is mourning his death,” she said.

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[Featured image: L-R: Danielle Dauphinais, Elijah Lewis, Joseph Stapf/Merrimack Police Department]