Ann Fox Smith, a special education teacher, was found stabbed to death in her home on Whitney Drive in Aiken on Aug. 25, 2008, after she didn't show up for work.
Although no suspects or persons of interest have been revealed, Aiken Public Safety released a criminal profile on Wednesday developed by Michael Prodan, with the SLED behavioral science unit.
Investigators think the crime was committed by a man who was very familiar with Smith, her home and her habits, and knew he would find her alone and vulnerable.
"This is not a random murder, ... there was a personal cause. The victim posed a problem and that problem was solved by the murder," Prodan said.
Prodan nor Aiken investigators have released any additional information about evidence, including the weapon the killer used, but have ruled out that the case was a rape or burglary gone wrong. Details on the killer's physical stature were also not released.
"There is an individual out there who may suspect or have knowledge of the murder," Prodan said.
Fear and misguided loyalty have kept those with information from coming forward, he said.
Prodan said investigators have learned from experience that offenders will follow the investigation and make comments about the crime and ask others non-committal questions about why it happened or who they think is the suspect.
"Investigators understand it may be difficult to come forward," Prodan said.
He said the person is still considered a danger to others and could strike out unpredictably to those around him if he sees them as a threat.
Prodan said there are several persons of interest who have not cooperated with the investigation.
Smith's daughter, Lauren, and her son, Larson, have been ruled out as suspects, according to Public Safety Spokesman Lt. David Turno.
A year ago, Turno said Smith's husband, William Smith Jr., was not cooperating with officers, but no information was released Wednesday on which family members, friends or suspects are still considered uncooperative.
Anyone with information in the case can call Crime Stoppers of the Midlands at 1-888-CRIME-SC.