Caveat: since this is a TV show, assembling an accurate profile on Red John is ridiculously difficult, if at all possible. The information with which the audience has been provided could easily describe several killers. However, for the sake of simplicity, let us assume that Red John's MO is still evolving.
Available data overview:
1) Technical
worker traits: electrician, carpenter, mechanic, plumber
- Strong
hands
- “Neither
muscular nor soft,” thus uses stun gun to subdue victims, also binding them with tight,
black plastic ligatures
- Uses
linoleum cutter – very specific tool, likely something from personal environment,
chosen due to availability and/or desirability
- Alias
“Roy Tagliaferro,” which translates to “cut iron” and could relate to an industry with which Red John is familiar
- Uses
rubber gloves to paint signature smiley face
- Carries
kill-kit with him, because the items used for murder have not been mentioned to have been present at the crime scene at the time of murder or afterwards; however, Red John seems to easily hide in plain sight, which would indicate he wears a uniform or disguise that justifies the items in his possession – it is not unusual for a repairman to carry duct tape or wire, etc.
- Attacks
low-risk targets – nearly all women, late at night, in their homes
2) Fiercely
intelligent, highly educated
- Alias
“Dr. Joe N. H.”
- Cites
William Blake’s “The Tyger,” which portrays the tiger as the embodiment of a
creator’s power, an animal of terrifying beauty, strength, and complexity
- “Showman
and artist”
- “Has
a strong sense of theatre” – signature smiley face more of an emotional release than the victim, wants the face to inspire dread and fear, ensures it is seen first
- Exhibits
psychopathic tendencies – uses a mixture of charm, manipulation, intimidation,
and violence to control others, in order to satisfy own selfish needs
- Narcissistic,
hates being belittled in public
3) Extremely
well-connected
- Has contacts
in the FBI
- Can
infiltrate CBI network, which indicates Red John is either a very capable hacker or has access to one
- Has
dedicated followers, “disciples”
- Bruno
Heller compares to Moriarty
4) Constantly
changing MO
- Reoccurring
frenzied stabbing and cutting of torso
- Rape
- Heat
suffocation
- Painting
toenails in blood
- Poisoning
- Shooting
- Kidnapping
With this data in mind, my money is on Ray Haffner.
Although all seven remaining candidates do not truly fit the profile, I would reject Partridge, because Red John is extremely sensitive to mockery and Jane has repeatedly ridiculed Brett in front of others. Stiles and McAllister seem likely, but their age would have been noted by Rosalind Harker. Kirkland appears too desperate to obtain Jane's research and does not fit the timeline of Lorelei's video. Smith could become Red John if the writers wish him to; there is virtually no background information concerning his character.
Bertram lusts for power and domination, and quotes William Blake in 3x16, but since Red John has been likened to Jane on numerous occasions, Haffner seems like the more reasonable choice.
Ultimately, all of the remaining suspects appear to be sloppy choices without proper justification. Their interactions with Jane have to be clearly explained or their alternate Red John will seem forced. Unless Jane is actually still in the mental hospital, trapped in a hallucination or some such.