Her name is Peggy Lynn Johnson. But for the past 20 years she was referred to simply as Jane Doe.

Johnson's body was found on July 21, 1999. It had been dumped in a cornfield in Raymond, Wis. She was 23.

Now the Racine (Wis.) County Sheriff's Office believes it has found the killer.

The suspect has been identified as Linda Sue LaRoche, a 64-year-old Cape Coral, Fla., woman, Racine County Sheriff Christopher Schmaling announced Friday.

"I would also like to add that until recent weeks, neither Linda LaRoche or Peggy Johnson's names have ever come up in our investigation," Schmaling said. "Also, Peggy was never listed as a 'missing person.' I think that is important to understand."

LaRoche faces the possibility of life in prison after being charged with first-degree intentional homicide and hiding a corpse.

LaRoche was arrested Nov. 5 by members of the Racine County Sheriff's Office in Cape Coral. Schmaling said that LaRoche will soon be extradited to Racine to "be held accountable for what she has been done."

It was not until a few weeks ago that Johnson was discovered as a possible identity for the Jane Doe, Schmaling said.

The tip that led to LaRoche's arrest came from "a concerned citizen" in Cape Coral who said that LaRoche had been "telling people that she had killed a woman back when she lived in Illinois," according to the criminal complaint. The Racine County Sheriff's Office heard about the tip on Sept. 23.

On Friday, Schmaling detailed the series of tragedies that led to Johnson's death.

"After her mother died, Peggy was approximately 18 years old, cognitively impaired, on her own, and went searching for help at a medical clinic in McHenry, Ill. There, she met a registered nurse named Linda LaRoche, who recognized Peggy's disability and took her into her home," Schmaling explained.

Johnson lived with LaRoche in McHenry for the next five years, during which Johnson "suffered long-term and horrific abuse at the hand of Linda LaRoche," Schmaling said.

Investigators said that, before her death, Johnson had suffered burns and blunt-force trauma to much of her body, a nose fracture, cuts to the head, abrasions to the forehead, a heavily battered left ear, and showed signs of being both sexually abused and malnourished.

Investigators recently interviewed LaRoche's ex-husband and five children, who all either lived in the home with LaRoche and Johnson or resided nearby.

The children told investigators that between 1994 and 1999 Johnson was taken into the home and was directed to "act as a nanny and housekeeper in exchange" for housing, according to the criminal charges filed against LaRoche.

According to the criminal complaint, LaRoche's children recalled the following:

Johnson often had signs of injuries caused by LaRoche. She had been forced to sleep in a crawl space under the home. LaRoche would be "verbally and emotionally cruel" to Johnson, "at times screaming at her like an animal." One of the children told investigators that LaRoche once stabbed Johnson's head with a pitchfork.

LaRoche's former husband described her as a "force to be reckoned with." He told investigators that one day in 1999 he came home from work and found Johnson dead on the floor.

"LaRoche told him Peggy had overdosed and she was going to take her away," according to the criminal complaint.

"He recalled LaRoche being gone for approximately 2½ hours and then returned home without Peggy."

The tale that LaRoche told investigators about Johnson's death goes like this: LaRoche came home and found Johnson standing on a counter, pouring a bottle of pills down a drain. A few minutes later, Johnson fainted.

LaRoche, who is a registered nurse, "stated she didn't know what to do and that she thought about calling an ambulance but didn't," according to the complaint. She claimed that Johnson's eyes were still fluttering, and she decided "she couldn't handle Peggy anymore," so she took Johnson to her grandmother's home.

Upon interviewing Johnson's grandmother, she told investigators she had never met LaRoche. Then, investigators said that LaRoche "changed her story and admitted that she was not sure who the person was that she left Peggy with."

The next day, she changed her story again. This time, she said she drove to Wisconsin, let Johnson out of the car in a rural area and drove away.

"LaRoche asserted that Peggy was not injured at all when she dropped her off and that something must have happened to her after she dropped her off," investigators reported, "contradicting the information regarding the condition of Peggy's body at autopsy."

Finding a suspect

Johnson's parents and brother are deceased, although she does have a surviving sister whom she never met, Schmaling said. Her body is to be exhumed from its resting place and will be reburied next to her mother's grave in Belvidere, Ill.

With Johnson not being listed as a missing person, it could explain why she was not identified over the past 20 years as investigators pored over more than a thousand missing person cases and Johnson's DNA was added to a missing persons database.

In October 2013, her body was exhumed for forensic isotope analysis. It was reinterred at Holy Family Catholic Cemetery in Caledonia, Wis., on July 21, 2015, the 16th anniversary of the day she was found. Johnson's DNA was used to locate surviving family members and confirm her identity.

During Friday's news conference, Schmaling said: "We are very proud today by the fact that we can finally offer some closure and bring some peace."