A woman accused of killing her nine-year-old son and burying his body in her Detroit backyard has been charged with murder, a prosecutor said Wednesday.

A shallow grave holding the remains of Zemar King was discovered on Jan. 6 while the landlord was preparing the house for new tenants.

No details were released at that time although Detroit police acknowledged an investigation was underway.

Zemar was smothered to death on Oct. 24, two weeks before his 41-year-old mother left for Georgia with a three-year-old son, Wayne County prosecutor Kym Worthy said.

"I have been a prosecutor for a long time, and I often say that I have seen it all. The horrors of this child abuse case defy that," Worthy said.

The mother was arrested Jan. 10 in an unrelated case in Cobb County, Georgia, online records show. She was awaiting extradition to Michigan on a murder charge and other crimes.

"This case is rather shocking," said Todd Bettison, Detroit's interim police chief.