Kathy Gloddy Murder Possible Break in New Hampshire

Cops See Break in 1971 New Hampshire Murder.

Sisters of 13-Year-Old Rape-Murder Victim Hail Stunning Developments, 38 Years Later.

Autumn brings a chilling memory for many residents of Franklin, N.H. It’s the time of year when Kathy Gloddy, 13 at the time, vanished in broad daylight almost 40 years ago.

Kathy Gloddy, 13, was attacked in small New Hampshire town after ice cream stop.

Hopes for solving the case have dwindled over time. But new developments — and the involvement of a private investigator — could mean the mystery is finally on the verge of being cracked.

In late November 1971, Kathy left her home on a trip to a store for ice cream. In tow was her constant companion, a German shepherd named Tasha. When Tasha returned home and Kathy did not, family members grew concerned.

“The dog climbed up on the doors and was clawing at the door, just scratching at the door to get in,” Karen Gloddy, one of Kathy’s sisters, told ABC News. “The dog ran around the house, searching for her.”

Watch the full story on “20/20″ tonight at 10 p.m. ET

Stricken with panic, the family set out to find Kathy.