A North Carolina woman was sentenced to life in prison without parole for killing her estranged husband’s co-worker in a jealous rage because she mistakenly thought the woman was having an affair with him, PEOPLE confirms.

On Wednesday, Marlene Johnson, 66, collapsed after a jury in Rowan County found her guilty of first-degree murder in the 2013 stabbing death of Shirley Pierce, 62, local station WSOC-TV reports.

Johnson maintained her innocence even after the guilty verdict was read.

“I disagree with the jury’s decision,” she said in court, according to local station WBTV.

“I am innocent. I was never there. I would never hurt anybody. I would not have killed Shirley Pierce.”

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Judge Stuart Albright responded by saying that DNA evidence found at the scene “squarely contradicts everything that you just said,” the Salisbury Post reports.

After handing down her life sentence without parole, the judge then said to her, “Ma’am, you will die in prison. That is my order.”

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Johnson reportedly killed Pierce because she mistakenly believed she was having an affair with her estranged husband, Ervin Johnson, the Post and WBTV report.

Now retired, Ervin Johnson was the chief financial officer and president of Tuscarora Yarns in Mount Pleasant, the Post reports.

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Pierce was the executive administrative assistant to Martin Foil, the company’s chief executive officer, according to the Post.

View photos Shirley Pierce More

Johnson had harassed and stalked Pierce before the murder, according to trial testimony, the Post reports.

Before she died, Pierce had obtained multiple restraining orders against Johnson, the Post reports. Investigators who searched Johnson’s home and vehicle found surveillance photos of Pierce at her home and at work.

On July 23, 2013, Pierce’s fiancé, Chuck Reeves, found her stabbed to death inside her home. She had been stabbed once in the neck, which severed her jugular vein and carotid artery, the Post reports.

In court, Pierce’s only daughter, Tracy Pierce Brown, stood before the judge and talked about the impact her mother’s death had on her.

“She was everything to me,” Brown said, the Post reports.

Calls to Johnson’s attorney for comment were not immediately returned and it is not clear if she intends to appeal.