CONCORD, N.C. — He was referred to as the boy under the billboard for decades -- his remains were found near Raleigh under a highway billboard two decades ago.

Now, his dad has officially been charged with his murder.

NBC Charlotte has learned there's a connection to the Charlotte area. The mother and son killed lived in Concord. 

WCNC went to Mebane, just outside of Raleigh, late last year when the boy was still unidentified. 

RELATED: Remains found under NC billboard in 1998 identified as boy, 10

For years, 10-year-old Robert Adam Whitt's identity remained a mystery. The case was revived when Orange County Investigator Tim Horne connected with a genetic genealogy consultant and discovered a possible cousin.

Investigators then developed a scenario in which John Russell Whitt killed his son and his wife and dumped their bodies along Interstate 85. Horne says charges in Myoung Hwa Cho's death may follow. Her body was found in a Spartanburg field in 1998.

Whitt is in a Kentucky federal prison for robbing people at ATMs and carrying a weapon during those robberies.

Detectives believe both mother and son were killed in Concord, and their bodies were disposed of in two different Carolina cities.

The Associated Press contributed to this report.