She and her colleagues were out on a rural piece of South Carolina land Thursday morning, preparing to serve a search warrant.
She asked the other deputies whether they heard the banging, too. But it was hard to tell. It could have been just some noise coming from the woods, someone said.
The deputies listened more closely, and hearing it again they moved closer to a 30-foot-long shipping container and knocked on the side.
Inside Kala Brown, missing since late August, started screaming. "Help me! Get me out of here!" Spartanburg County Sheriff Chuck Wright told Ashleigh Banfield of HLN's "Primetime Justice."
The deputies took a padlock off the doors of the container and opened it.
Inside they found the 30-year-old woman tethered by the neck, "chained like a dog," the sheriff said.
I've been in here for two months, she told the deputies, who found tools on the property and cut her free.
"It's just a miracle by God that we found her alive," Wright told HLN.
There was no sign of Brown's 32-year-old boyfriend, Charles David Carver, who also disappeared in August.
Later, as dozens of people searched the 100-acre property, his vehicle was found. It was in a ravine, covered in brush.
A cadaver dog picked up on something, but it's not clear what, Wright said.
Brown told deputies she thinks four people might be buried on the property, which is owned by Todd Kohlhepp, the sheriff said. Kohlhepp, a registered sex offender, was arrested.
Kohlhepp is not cooperating with investigators, Wright said.
The sheriff described the container as a hellish place to be locked in during the area's hot weather. No lights, no windows, no air flow. Two visits a day, where Brown was given food and water.
She was wearing clothes when she was found. It's not clear whether they are the same ones she was wearing when she and Carver went missing.
Wright told the media that investigators think Kohlhepp, Carver and Brown may have known each other, but their relationship wasn't clear to authorities.
"I don't think this was a random act," the sheriff said.
Kohlhepp, 45, was added to the South Carolina Sex Offender Registry as a result of a 1987 kidnapping conviction in Arizona when he was a teenager.
Wright thanked the efforts of the Spartanburg County sex crimes investigators for leading them to the Kohlhepp property.
The sheriff said deputies found weapons on the property.
He described the property as a farm that has no home on it. Kohlhepp doesn't live on the property but was arrested there. It is unclear whether he has an attorney but he asked for one when he was arrested.
Police were still searching the property Thursday night.