HAMPTON - The circumstances surrounding the death of 85-year-old Alice Keyho remained a mystery Thursday, several days after her body was discovered by her sister inside the home they shared on Philbrook Terrace.

Authorities are still calling the case an "untimely death," but Deputy State Medical Examiner Jennie Duval has not determined the cause of Keyho's death, Senior Assistant Attorney General Michael Delaney said Thursday night.

The autopsy itself was completed on Wednesday, but it is unknown how long it will take to determine how Keyho died, Delaney said.

"Conducting an untimely death investigation into the circumstances surrounding the death of an elderly woman can be an involved process," he explained. "All of the authorities participating in that process right now are doing everything they can to ensure that a thorough and complete investigation of this matter is being conducted."

Delaney confirmed that any medical conditions Keyho may have had will be considered in the state medical examiner's investigation. He added that he couldn't comment on whether she had been ill or had any pre-existing medical problems.

Keyho lived with her sister, Helen Garland, 74, at the single-story ranch home at 10 Philbrook Terrace. Garland discovered her sister at 6:40 a.m. on Tuesday and called 911. Delaney would not say where Keyho was found inside the house.

He said first responders noticed visible injuries on Keyho's body when they arrived, but he declined to say what those injuries were.

Members of the state police Major Crime Unit, headed up by Sgt. Shawn Skahan and assisted by detectives from State Police Troop A in Epping and Hampton police, were still actively working on the case Thursday.

"Police have continued to investigate the death actively throughout the course of yesterday and today," Delaney said on Thursday. "They continue to examine information and interview witnesses in an attempt to learn as much as possible about Mrs. Keyho's activities."

Garland is staying with a friend in Hampton and has cooperated with authorities, he said.

Funeral details for Keyho have not been released. In addition to her sister, she had relatives in the North Andover, Mass., area, including a brother. Keyho was not married and did not have any children.

The yellow crime-scene tape that had encircled the home on Tuesday and Wednesday was removed Thursday, and there was no longer a police officer stationed in front of the house.