The blood of 53-year-old David Gibson was washed away by bleach.
And along with it could have been evidence leading to his killer, a forensic expert said Thursday.
Just as the cleaning - performed by a member of Gibson's family - was completed Tuesday morning, authorities returned to the Ooltewah residence where Gibson's bludgeoned body was found Monday. This time, they were armed with information from the Hamilton County medical examiner that they were working a homicide.
Investigators with the Hamilton County Sheriff's Office collected some evidence Monday night at the 6437 Snow Hill Road home before allowing a next-door neighbor to sign papers releasing the residence from the investigators' custody. At that point, detectives had ruled Gibson's death "suspicious."
"They did [release it], but they're back out there now," Carolyn Porter said Wednesday night, glancing toward a sheriff's office car guarding the Gibsons' driveway. Porter was the neighbor who signed the investigators' paperwork.
In the time the scene was left unattended by investigators, a family member went into the house and used bleach to clean up the bloodied area where Gibson drew his last breath, the Chattanooga Times Free Press has learned.
Lawrence Kobilinsky, professor and chairman of the Department of Sciences at John Jay College of Criminal Justice in New York, said the entry tainted the crime scene.
"Now the scene is completely compromised and contaminated," he said. "You have a civilian simply going in and destroying evidence. The scene should have never been released until a cause of death was determined. Now evidence could be gone."
According to the autopsy, Gibson sustained nine head wounds and was so bloodied that investigators at first weren't sure how he died. Investigators have not specified whether someone forced entry to the home or what was used to bludgeon Gibson.
The home has remained in the sheriff's custody since Tuesday, with a reserve deputy posted at the driveway. A marked car remained at the residence throughout the day Thursday. The Gibsons' gray cat lingered near the stairs at the empty home.
"They [investigators] just had a couple of things they wanted to check out," said Sheriff Jim Hammond. "I don't think they took the scene back."
Hammond said even though the scene was cleaned before the case was officially ruled a homicide, he doesn't believe it will hurt the department's chances of catching Gibson's killer.
He would not say whether it was a mistake to release the scene before determining Gibson's cause of death.
"I can't say it was or it wasn't. I can't say. I don't know what they [investigators] went back for," he said. "I'm sure all of that will come out when they are ready to present the case."
Hammond declined to release any other details.
Gibson suffered from alcoholism and mental illness and spent years incarcerated, according to court records.
He was charged with assault in 2009 after threatening to kill a man, records show, and was released from jail a couple of months ago.
His mother once again took him in and cared for him - he was her oldest child - despite his troubled history documented in court records.
A family member, who asked not to be named, said Gibson had attacked his mother in the past. In one incident he covered her mouth and stabbed her five times in the chest with a pocketknife.
Witnesses said she left the residence in fear Sunday night. She came back Monday morning and found his body, the medical examiner's report states.
His mother could not be reached for comment.
Family friend Wayne Chambers said he had known David Gibson since 1980. Gibson used to build homes then and worked with Chambers, who owned a carpet business.
"All through the years, David has been a friend to me. Nothing but nice," he said.
Chambers said Gibson's life was never the same after a divorce in which his wife was given custody of their two boys.
"To me, he just couldn't handle it. He didn't know what to do. That's when his problems began," Chambers said.
Anyone with any additional information about Gibson's death can contact Hamilton County Sheriff's Office at 209-8940.