ETA MOO here-- It seems now that some kind of time had to pass to start a decomp scent, at least a few hours you'd think, before a cadaver dog could hit on the scent. Is it possible SS did take Jenn's Nissan the night after he had put MS in the field, and somehow then picked up the decomp scent onto Jenn's wheel well. Maybe @Seattle1 was on the right track, after all. It just seems he'd have to have driven to the body or somehow touched the body in some way then transfer it to Jenn's wheel well. Or like some clever member suggested hidden body in wheel well.
Warning graphic talk of decomp & cadaver dog info
From doggiesaurus com:
(No, on mortally wounded, I believe must be deceased.) Cadaver dogs should be able to detect bodies 24 to 72 hours soon after death, as this is when decomposition starts. Then can also detect human remains a long time after death, being used by archaeological teams. The bottom line is cadaver dogs can be trained to detect human remains the moment the body starts to decay.
It's a very interesting article you might want to read the whole article. The dogs are amazing!
Not even 12 feet of soil can get between these dogs and a corpse.
www.inverse.com
These dogs have their work cut out for them. Unlike drug- or bomb-sniffing dogs that just need to identify a few specific scents, cadaver dogs must learn to identify hundreds.
Training requires a lot of exposure to a lot of putrid odors, but acquiring isolated versions of those odors isn’t easy....
[...]
When cadaver pups first start out, they practice not with real corpses but with synthetic cadaver scents. These are a real thing: the chemical giant Sigma-Aldrich makes three different corpse scents for canine training, including “recently dead,” “decomposed,” and “drowned victim.” But when it comes to the scent of dead bodies, nothing beats the real, multifarious stench. Human bodies decompose in five basic stages, and each of those stages...
[...]
Many of these scents are likely identifiable only by trained dogs, but a few will stick out even to the common human nose: cadaverine, putrescine, skatole, and indole. As Inverse has explained in the past, these compounds smell particularly rank:.....
Decomposition is the process by which organic material is broken down into simpler forms. It occurs
forensicsdigest.com
Stage 1 Fresh (1-2 days) This stage begins almost instantly from the moment of death. As the heart stops beating, the body’s cells gets deprived of oxygen and pH changes occurs.
Stage 2 Bloated (2-6 days) This stage of decomposition includes the first …
Stage 3 Decay (5-11 days) The previously inflated carcass now deflates and …
Stage 4 Post-Decay (10-24 days) By the time this stage is reached, …