A South Carolina man charged in the kidnapping of a woman found alive in a storage container confessed on Saturday to the unsolved killings of four people in 2003, and may be linked to a total of seven deaths, the authorities said.

Late on Saturday, the Spartanburg County sheriff, Chuck Wright, said that a body found in a shallow grave the day before was that of Charles D. Carver, 32, the boyfriend of the rescued woman, The Associated Press reported. He died of gunshot wounds, Sheriff Wright said.

Todd C. Kohlhepp, 45, the owner of the property and a registered sex offender, has been charged with kidnapping the woman, Kala V. Brown, who disappeared along with Mr. Carver in late August.

Investigators had been sweeping the 100-acre woods and fields with cadaver dogs after finding Ms. Brown inside a storage container on the property, about 20 miles east of Greenville, S.C. The sheriff said there were indications that two other bodies might be buried on the property.