Oct. 29, 2009 -- Each year, thousands of children and young adults vanish without a trace. For families searching for their missing loved ones, it can become a costly and emotionally overwhelming pursuit. That's where private investigator Tom Shamshak comes in.
For the past 10 years, Shamshak, 59, a retired police chief from Winthrop, Mass., has worked pro bono to help families track down their missing loved ones. He also works as program director of the Certificate in Professional Investigation program at Boston University, where students are trained over six months to become private investigators.
"At this point in my career, it's about giving back," he said. "I think it's the right thing to do."
His most recent case involves a 38-year-old murder mystery that will be featured on "20/20" Friday.
At 13 years old, Kathy Lynn Gloddy was found raped and beaten to death just a mile from her home in Franklin, N.H. For nearly four decades, her family searched for answers and justice. After seeing Shamshak on an earlier "20/20" broadcast, Gloddy's family solicited him to work on Kathy's case in May 2009.
"Kathy Gloddy left her home sometime around five o'clock and walked a short distance away to a convenience store," Shamshak said. "We know that she purchased some ice cream and some potato sticks, her favorites. ... From there, she is seen walking in the parking lot at the Franklin high school, and that's the last anybody has seen of her ... while she was alive.
"Her body was found here on 1 p.m. the following day on the 22nd of November," he added. "She was found ... on her back, clothed only in a pair of knee socks. ... She had been run over by an automobile that came in back over here. A hunter coming through the area [and] thought it was a deer carcass, but came closer to the area and discovered that it was Kathy Gloddy's body."
A major break in the case came 38 years later, from 10 states away, and police now have a prime suspect.
Shamshak, a hardened investigator, called the Gloddy case a "savage killing."
"It's one of the most heinous crimes that I have encountered in my 31 years of professional experience," he said.
Watch Kathy Gloddy's story on "20/20" Friday at 10 p.m. ET