Rapid City authorities say they have solved a cold case after more than 50 years.

In a press conference Monday afternoon, Rapid City Police Chief Karl Jegeris spoke alongside Detective Wayne Keefe as they outlined the evidence that pointed to Eugene Carroll Field, a previously unknown suspect, in the 1968 murder of Gwen Miller.

"Today, there's a slight celebratory mood because the case has been solved," Jegeris said. "But I assure you, the fact of how horrific this crime was wears heavy on each and every one of our hearts."

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Miller, a 60-year-old pharmacist, lived alone in Rapid City, and had failed to show up for work on Feb. 29, 1968. Her coworkers feared a health issue related to her diabetes, but they found the glass on her home's back door smashed when they arrived.

Police found Miller dead in her bed, with no signs of a struggle in the room. But an autopsy showed that she'd been sexually assaulted and strangled to death.

Fingerprints were taken and tested, witnesses were spoken to, suspects were interviewed — but nothing ever came of the case, and no one was ever arrested.

Further efforts were made in 2005 and 2010, but although authorities managed to get a DNA profile from the suspect, they were unable to determine anything more.

Detective Wayne Keefe works part-time investigating cold cases, and he has been working on the Miller case since 2016, interviewing over 100 people during that time.

Keefe reached out to IdentiFinders, a forensic genealogy firm run by Colleen Fitzpatrick, for assistance in the case.

Fitzpatrick explained at the press conference the process of using genealogy records to find possible genetic matches to a DNA sample — the same tactic used to solve the Baby Andrew case in Sioux Falls earlier this year.

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She came back to police with connections to someone with the last name of "Field" or "Fields" — names that had no prior mentions in the investigation or connection to the case.

Using that information, Keefe identified Eugene Carroll Field — a ticketing agent for Western Airlines at the Rapid City Regional Airport, which Miller frequented. He also determined that Field had rented a room in the house next door to Miller for several months in 1963.

Keefe interviewed two women who had been married to Field, both of whom reported abuse from their former husband. He also contacted Field's only sibling — a brother who provided a DNA sample.

That DNA sample, when analyzed and compared to DNA from the crime scene, showed a 99.23 percent probability of being from a full sibling.

Keefe said there was enough evidence to charge Field with first-degree murder — but he died in June of 2009, the result of a tumor in his throat that grew until it cut off his air supply.

Multiple members of Miller's family were in attendance at the conference, including her niece Kay Miller Temple, who spoke briefly, thanking authorities and everyone who's assisted with the case.

"The family of Gwen Vivian Miller offers you our gratitude and our appreciation," she said through tears. "Thank you for giving us an answer."