I was thinking about the Crown's closing remark to the jury not to lose their common sense. Here's why that's such a great closer for the prosecution.
If Garland is not the murderer then he is the unluckiest person on the planet. Someone with a truck the exact make, model, color and rust stains as Garland happened to arrive at the murder scene the same early morning hours the victims went missing; the victims are people Garland happened to know and happened to have a grudge against; he happened to have researched them recently online as well; he happened to research kidnapping, torture and murder just when neighbors of his were about to be kidnapped, tortured and murdered; he happened to be into adult diapering and the victims happened to have on adult diapers; even though there were no livestock on the farm, Garland's collection of meat hooks and cleavers is not suspicious because everybody knows collecting meat hooks and cleavers is just normal, good family fun; he happened to be into locksmithing and the victims' house happened to be accessed through a picked lock; of all the vehicles Kathy decided to bleed on before getting murdered, it happened to be Garland's truck; of all the knives and hooks the victims decided to bleed on, they happened to be Garland's; the crime scene happened to be free of the murderer's DNA and Garland just happened to have laying around some DNA cleaner and haz-mat suits; the victims were two adults and a child and, has bad luck would have it, two adults and a child happened to be photographed laying deceased on Garland's property a day later; the murderer happened to incinerate the bodies in Garland's burn barrel for many hours with neighbors noticing the unusual smoke and flames, but Garland himself happened never to notice the incineration or the grisly remains; and, of course, he is most unlucky when it comes to his footwear since: (1) the murderer happened to wear sneakers the same size and brand as a shoebox Garland had on hand, (2) the victims happened to bleed onto Garland's rubber boots -- especially unlucky since Garland had never even met Nathan before, and (3) the victims were so inconsiderate as to put their blood on the sneakers Garland happened to be wearing when arrested.
(Any lack of seriousness in the above is meant as sarcasm not insensitivity to this horrific crime).
I'm sure I missed some things and I apologize if I got some minor details mixed up from memory, but I think you get the gist. Even without the bodies or the culprit's DNA at the initial crime scene, as long as common sense prevails this is as open and shut a conviction as it gets. IMO