Here's one source that quoted Sheriff Fitzgerald:
"On Wednesday, Barron County Sheriff Chris Fitzgerald said 56-year-old James Closs and 46-year-old Denise Closs deaths were ruled a double homicide.
'[Jayme's] parents died from gunshot wounds that's why we are ruling this a homicide. There was no gun found on the scene. We believe Jayme was home based on the evidence in our case. Some of it from that 911 call and some of it is still part of the active investigation and we're not able to comment on why we believe that,' said Fitzgerald."
Sheriff: Jayme Closs was home at time of murders
As far as the source of the "particularly interesting" description, I pulled that from the facts assembled by WS moderator Whiskers16 on the first page of each of these Closs family threads. That post reads: "The department says at this point there are no signs of drug or alcohol use and say this case is particularly interesting as there were no weapons found on scene. [15]"
That post is pulled directly from an article by WEAU, which can be found by scrolling down through several other articles at this website:
UPDATE: Sheriff: Missing girl was in home at the time of the murders