Ericka Lotts waited three months for a jury to tell her what she always believed — that her first-born child, Derontae Martin, did not fatally shoot himself at a house party in rural Missouri, reports NBC News.

On April 25, her son was found unconscious in an attic closet, dead from a gunshot wound to his left temple. Martin was at the Fredericktown home of a White man who has posted racist memes on social media, which NBC News has viewed.

Lotts, 37, said authorities concluded that Martin, 19, who was Black, died by suicide and repeatedly told her that she was in denial about the nature of her son’s death.

Lotts felt publicly vindicated on July 30 after a jury of six people ruled during a coroner’s inquest hearing that Martin was killed by violence.

“I already knew he was killed violently. It wasn’t a shock to me,” Lotts said. “I was just happy they let it be known that somebody needs to speak up and let these people pay for what they did.”

NBC News obtained investigative documents from the police investigation into Martin’s mysterious death from a doctor who performed an independent autopsy. Records show that police investigated allegations of racism and foul play by the homeowner. NBC News is not naming him because he has not been charged with a crime.

Police and medical personnel who handled the initial death investigation were blinded by tunnel vision, Lotts said.

“This is what they wanted it to be,” she said. “When they walked in that house and they seen Derontae was a Black male, they were sure he had shot himself. That’s all the information they needed.”

A witness told police in June that he had a conversation with the homeowner at a Walmart in May and that the homeowner used a racial slur before admitting to having participated in Martin’s death, according to a report from the Missouri State Highway Patrol.

According to what the witness told police, the homeowner approached him and asked whether he wanted to “come out there and kill some n——.” When the witness declined, police said, he asked the homeowner whether the rumors were true that he was responsible for Martin’s death.

“Damn right I did,” the homeowner told him, according to the witness statement. The witness then told police how the homeowner “described ways to get away with murder via wearing gloves, face coverings, etc,” the highway patrol report said.

The homeowner could not be reached for comment during the past week.

Reports said investigators with the highway patrol asked the homeowner about the alleged conversation with the witness. The man told police that he may have used racial slurs, but he rebutted an admission of murder.