The man accused of killing a 30-year-old south Georgia teacher and concealing her death pleaded not guilty to all charges Thursday.

Ryan Alexander Duke, 33, has been charged with murder in the death of Tara Grinstead, a former beauty pageant queen and popular teacher reported missing in 2005. Duke waived his arraignment Thursday and did not appear in the Irwin County courtroom.

By the time Grinstead was reported missing in October 2005, she was likely already dead, according to investigators. But no arrests were made in the Grinstead's disappearance until February, when the GBI announced a major break in the case.

Duke was a 2002 graduate of Irwin County High School, where Grinstead taught history. But details about the relationship between the two have not been released. Grinstead was last seen on Oct. 22, 2005, when she left a cookout and said she was going straight home. Two days later, she was reported missing when she didn’t show up at work.

Investigators now believe Duke killed her in her home and then moved her body to another location, possibly a farm in neighboring Ben Hill County.

A second man was later arrested and charged with concealing the death of south Georgia teacher Tara Grinstead, according to arrest warrants. Bo Dukes, 32, allegedly helped Duke “conceal and destroy” Grinstead’s body. Dukes is not related to Duke, but the two were high school classmates.

In April, Duke was indicted on six counts, including malice murder, felony murder, aggravated assault, burglary and concealing the death of another.