Boy, 10, whose body was found beneath billboard in 1998 lived in Concord

MEBANE, N.C. — Decades after the unidentified bodies of a woman and a 10-year-old boy were found in separate states beside a Southern interstate highway, investigators say they were a mother and son and that the boy's father has confessed to killing them.

[ALSO READ: Missing boy last seen 2 years ago in Massachusetts found safe in Florida]

The case was cracked thanks to an online DNA database, help from international police and a consultant whose work led to an arrest in the Golden State Killer investigation, authorities in North Carolina and South Carolina said Tuesday.

Investigators identified the 10-year-old boy as Robert "Bobby" Whitt, who in 1998 also disappeared from his fourth-grade class in Concord.

A Channel 9 viewer, Stephen Kenny, saw Channel 9's report and recognized Whitt as his friend from school who vanished 20 years ago.

Channel 9 showed Kenny a picture of the boy.

"That's my buddy, Robert,” Kenny said

Investigators in both states said they would never stop trying to solve the 1998 cases that they never knew were related, separated by 215 miles apart along Interstate 85.

"I always kept the case file box under my desk, where it was purposefully in my way. Every time I turned, I hit it with my leg. I did this so the little boy couldn't be forgotten," said Orange County Sheriff's Maj. Tim Horne, who worked the case from the beginning.

For more than two decades, Kenny’s friend, Bobby, was a nameless victim found under a billboard in Mebane, near Greensboro, almost two hours away from Concord.

North Carolina authorities even enlisted experts to create a sketch and a bust reconstructing the appearance of the child. But despite widespread dissemination, no one was able to identify him.

Kenny only knew that in 1998 his friend's mother went to visit family and never returned. A little later, Whitt left to reportedly visit his mother and aunt in Hawaii.

Weeks later, Kenny went to tell his friend about his new teacher assignment.

Whitt's father answered the door with bad news.

"Robert is not coming back,” he told Kenny.

Kenny didn't know about the woman's body found off of I-85 near Spartanburg, and the child found off the same highway three hours away.

For two decades, Kenny continued to search online and social media.

"Over the years, I have never forgotten about him,” Kenny said. “I've always remembered him."

Investigators never knew the identities of the bodies found until new DNA technology allowed them to link mother and son, then the father in prison on other charges who police say confessed to killing them both.

Investigators had no idea the cases were linked until December 2018, when consultant Dr. Barbara Rae-Venter reviewed the latest DNA tests on the boy's body, Orange County Sheriff Charles Blackwood said in a statement. Rae-Venter's work with online DNA databases had earlier helped lead to an arrest of a man in California charged with 26 counts of murder and kidnapping in California in the 1970s and 1980s.

The boy's remains were found in September 1998 by workers mowing grass on a frontage road near I-85 in Durham, North Carolina, Blackwood said. DNA testing showed he had Asian and Caucasian parents.

Rae-Venter matched the child's DNA to DNA from a close relative who had submitted the information to an online database. After contacting the relative, investigators learned the boy was Robert "Bobby" Adam Whitt, who was born in Michigan and raised in Ohio, Blackwood said. He also said they were given strong evidence his mother -- who had disappeared the same year as her son -- was also dead.

[ALSO READ: DNA testing that caught 'Golden State Killer' leads police to suspected NC serial rapist]

Meanwhile, deputies in South Carolina had found an unidentified woman whose nude body was dumped in the woods beside I-85 in May 1998, Spartanburg County Sheriff's Lt. Kevin Bobo said. Her hands had been bound and she had been suffocated.

After DNA testing confirmed the victims were mother and son, investigators in the United States enlisted the help of Korean authorities and international police to identify the woman as Myoung Hwa Cho.

Cho's husband, the boy's father, is serving time in federal prison on unrelated charges. After being questioned several times, he confessed to killing his wife and son, Bobo said.

Authorities aren't releasing his name because he hasn't been charged in the killings yet. Charges may not be filed until investigators figure out exactly where the two victims were killed, Bobo said. Investigators think the woman and her son were killed somewhere else and dumped beside the interstate.

Kenny said he learned about Whitt’s death Thursday morning while watching Channel 9.

“I just jumped out of bed, paced around the room, called my mom,” Kenny said.

The search ended sadly for him, but he finally knows why his best friend never said goodbye.

It's a relief, he said, "To know what exactly happened to your friend 20 years ago and just kinda close that book.”

Read more about the case here.

Associated Press