The Anachron:
The easiest way to describe the Anachron is that its a machine similar to The Matrix (the film) except the Anachron maps brain activity (like a PET brain scan) instead of sticking something into your head via a port. The Ananchron allows a living person to access the last few minutes of the life of a dead person. The Anachron provides an electromagnetic shock to the brain of a cadaver and maps the short term memory of the subject.
Here is the make-believe sci-fi bit: When a person dies
their brain stores their final memories. If a person dies due to high
trauma and stress their brain stores more information. The theory goes
like this... when you are in shock from an injury or stressed out your
brain slows things down and processes things differently than normal.
If you die when your brain is in this "overdrive mode" it stores all
that subconscious activity away better than if you die peacefully.
Trauma is like memory insulation. It packages things up better and
keeps them in tack better and longer.
The Anachron unpacks those stored memories and allows them to be transferred to another living person. The living subject experiences the dead person's final minutes firsthand as if they where physically reliving the memory. The living person essentially steps into the shoes of the dead person and relives the memory in real-time as the Anachron reanimates and scans the dead persons brain. It's like time traveling, but you become someone else and you can't change any outcomes. Also, everytime you use the Anachron you are living out someone's death. As the Proxy, your brain believes that the memories you are experiencing are real. You think you are someone else; every thought they had - you have, every action they take - you take, every pain they feel - you feel. Proxies die painful deaths every time they load in. The stress and fatigue that puts on them is excruciating.
It takes three people to use the Anachron. One is the "Proxy" the other is the "Operator" and the last is the dead person, the "Subject." The Proxy is the FBI agent and they are unconscious (a dream-like state) during the process as they are connected to the Anachron. The Subject is the dead person whose memories are being scanned and remapped to the Proxy. The Operator runs the machine and attempts to synchronize the Proxies brain waves to match those of the Subjects. If the Proxy doesn't keep their brain waves synchronized to the Subject the sequence aborts and the Proxy wakes ups.
The only people who can use the Anachron are people who naturally have a high empathy for other people. The proxy must become their subject for the duration of the sequence. Most people reject the Subjects memories; their brains can't suspend judgement and roll with it, they subconsciously say "this isn't real" and refuse to cooperate. Only people with high empathy have the mental ability to accept another person's memories.
The Anachron destroys the brain tissue of the Subject during the scan process so it can only be used once on a Subject. The scan cannot be recorded, it must be experienced by another brain in real-time, there exists no technology to store memories outside of the human brain. As the story begins the Anachron has only been used in lab testing. It's use in the story is it's first field test.