BARRON - Nearly two months after 13-year-old Jayme Closs disappeared amid the violent deaths of her parents, law enforcement, residents and observers remain confounded.

Jayme went missing on Oct. 15 after her parents, James, 56, and Denise, 46, were found shot to death in the family's home outside Barron. Jayme, who is believed to be endangered, hasn't been seen or heard from since.

Key questions linger about the events of that October night. USA TODAY NETWORK-Wisconsin went searching for some answers.

Why did the suspect(s) kill James and Denise, but not Jayme?

One aspect that doesn't add up for law enforcement and other experts is why the perpetrator(s) left James and Denise for dead, but not Jayme.

According Jack Levin, professor and co-director of Northeastern University’s Center on Violence and Conflict, it's unusual for a double homicide to be linked to a missing child.

"You almost never see this," Levin said.

Levin noted that there are cases in which a teenage couple kills relatives and runs off together. But Barron County Sheriff Chris Fitzgerald has indicated there's no evidence suggesting Jayme has a boyfriend.

Who called 911, and was there a delay between gunshots and the call?

The Closs' neighbor, Joan Smrekar, told USA TODAY NETWORK-Wisconsin that she and her husband heard two gunshots around 12:30 a.m. on Oct. 15. At 12:58 a.m., a 911 call came in from Denise's phone. But the dispatcher wasn't able to connect with the caller, so it's unclear who actually dialed 911.

Fitzgerald said the neighbors' account of gunshots is unsubstantiated, and nothing points to shots going off around that time. He's unsure why their time frame differs from investigators'.

"There’s nothing to show that somebody was in the house for 20 minutes," he said.

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How do police know Jayme was home at the time of her parents' murders?

Fitzgerald said in October that information from the phone call and from inside the home led investigators to conclude that Jayme was home during the incident. He would not elaborate further when asked by USA TODAY NETWORK-Wisconsin last week.

How did the suspect(s) get away?

The Closs' home sits along a two-lane highway outside of Barron, surrounded by woods. The road, U.S. Highway 8, is the main drag through the city and extends to surrounding areas.

Police arrived at the home just minutes after the 911 call. Given that factor, and the geography, it's difficult to imagine how the perpetrator(s) evaded law enforcement.

But Fitzgerald noted that someone can travel far in a car going 55 mph. And if the suspect(s) drove the opposite direction that police came from, he said, they had plenty of time to escape.

"Even though it’s a short time frame, it’s not impossible to get away," he said.

Was the incident random or targeted?

Fitzgerald has dubbed this the "million-dollar question," but authorities still haven't found the answer. And because this is such a rare case, Levin said, it's difficult to find others that compare.

Though police will continue to search, Levin cautioned that the case is likely to become cold soon. It's important to keep looking for Jayme and not give up hope, he said.

"It will be up to friends of the family to make sure that it’s not lost because then the victim will be lost," he said.