Inset: Karen Pais (Remembered.com). Background: Debra Patton at her trial for killing Pais in Tampa, Florida (WTVT/YouTube).

The relationship between two Florida sisters who lived together for a decade devolved to a point of one killing the other and burying her in a shallow grave in the backyard.

Debra Patton, 72, was convicted of second-degree murder in the death of 66-year-old Karen Pais in Tampa, according to the Hillsborough County State Attorney's Office.

The investigation began on May 29, 2021, when friends of Pais called cops after not hearing from her for several days, a probable cause arrest affidavit said. Deputies went to the home in the 11600 block of Cypress Park Street, where Patton denied knowing about her sister's whereabouts. The victim's car, purse, credit cards and ID were still in the home. Surveillance video from the home of a neighbor who happened to be a Hillsborough County deputy showed the victim enter the home on May 24, 2021, which was the last time she was seen alive. The video also depicted Patton throw several large trash bags into the garbage.

Cops noted a patch of fresh dirt in the backyard. Once they obtained a warrant, they dug up a 2-foot hole to find a trash bag in the shape of a body. They opened the bag to find a body that was suffering from a gunshot wound to the chest with a "Karen" necklace. A medical examiner later identified the body as Pais.

Patton told cops in an interview after receiving her Miranda rights that she had an issue with her sister but refused to expand on it. She denied killing her.

Pais' friends said she had told them that if she ever went missing or ended up dead, it was her sister who was responsible. They described at trial about the sisters' deteriorating relationship.

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"Debra was not interested in joining us anymore," her friend told jurors, according to a courtroom report from local Fox affiliate WTVT. "She would walk by to take the dog out and not speak to us. Just got rather cold, distant."

As Pais remained missing, her friends continued to press Patton for information, especially after deputies discovered the fresh dirt.

"She asks her, 'Is Karen in that hole? Is Karen in that hole?'" a prosecutor reportedly told jurors.

Patton ignored them.

Per WTVT, the case took several years to come to a resolution because of court delays and the defendant having been deemed incompetent to stand trial for a period of time.

Patton is set to be sentenced on Feb. 16.