A third body has been found at the property of a South Carolina man linked to seven deaths and the kidnapping of a woman who was found chained inside a storage container.

Todd Kohlhepp, 45, became a suspect after the Kala Brown was found on Thursday chained by her neck and ankle in a metal storage container on his 95-acre property near rural Woodruff.

The body of her boyfriend Charles Carver was found a day later. The couple had been missing for about two months.

The other remains were found near one another on Sunday and Monday, and the authorities are not sure who they are.

Following Kohlhepp's arrest, he confessed to a 2003 quadruple killing at a motorcycle shop in the small town of Chesnee, said Spartanburg County Sheriff Chuck Wright.

He was denied bond on Sunday on four murder charges for gunning down the motorcycle shop's owner, service manager, mechanic and bookkeeper.

Kohlhepp is charged with kidnapping the woman, and more criminal counts are expected. He has chosen to represent himself and not hire a lawyer.

As a teenager, Kohlhepp was sentenced to 14 years in prison in Arizona for binding and raping a 14-year-old neighbour at gunpoint.

He was released in 2001, and managed to obtain a real estate licence in South Carolina in 2006. The search for human remains has now expanded to other properties he owns or used to own, including places outside South Carolina.

Kohlhepp showed investigators on Saturday where he says he buried two other victims on the property he bought two years ago.

Kohlhepp did not tell investigators who was buried there.