(NewsNation) — The killing of four University of Idaho students is drawing parallels to a 2004 murder of two women that was solved following a break in the case that came some 11 months after the killings.

It was Halloween night in Napa, California, when Adriane Insogna and Leslie Mazzara were stabbed to death inside the three-bedroom home they shared with another roommate.

The pair were found almost immediately by the third roommate, whose bedroom was on a lower floor and who’d heard the killer creep up the stairs. It was a bloody crime scene, and the killer had left a smudge on the blinds on a kitchen window.

But days became weeks, and then months, and no one was arrested. Police collected 266 pieces of physical evidence — more than twice as many as the police in Moscow, Idaho, have in the quadruple-homicide.

Police in Napa interviewed more than a thousand people and took DNA from 200 of them, but none of the samples matched the blood that was found on the blinds. There was also no match to cigarette butts that had been smoked down to the filter outside the home.

After almost a year, police got the break they’d been waiting for: the DNA from the blood and the cigarettes matched each other. The murderer was a smoker, and his brand was new, and uncommon.

One of the Napa detectives who saw the case through to its conclusion, Todd Shulman, spoke about the case Thursday on NewsNation’s “Banfield.”

From the get-go, “we felt strongly this person had laid in wait planning his attack,” Shulman said, because several cigarette butts were found in the backyard.

Forensic testing revealed that the DNA on the cigarettes matched that in the blood found on the kitchen blinds. The cigarettes were Turkish Gold, a variation of Camels that were unusual.

Police released the information in hopes of getting help from the public. It came days later when Eric Copple turned himself in.

Though Copple was on an initial list of people from whom to obtain DNA evidence, he was “not at the top” because he had a “tangential association” with the victims. His fiancée at the time was friends with Insogna.

Police believe Insogna was encouraging her friend and Coppel’s fiancée, Lily Prudhomme, to leave him, which ignited a spurt of rage. Coppel and Prudhomme would eventually get married in the time between the killings and his arrest.

He also attended the funerals of Insogna and Mazarra.

“He made a point of burning his clothing after the fact, but other than that, he tried to keep himself in the mainstream of what his normal life was,” Shulman said. “It’s hard to say for sure if (his fiancée) knew and what she knew.”

Police in Moscow, Idaho, have released few details about the case and any relevant forensic evidence that might help lead to an arrest. It’s frustrated and angered the victims’ families and larger Moscow community.

“The family and friends should be patient,” Shulman said, “because I’m hoping some of that forensic evidence will yield some results and give detectives a firm direction to go in.”