WARNING. HERE THERE BE BLOOD AND MURDER STUFF. DO NOT CONTINUE IF IT WILL TRIGGER ANYTHING/MAKE YOU QUEASY. PLEASE. PLEASE. PLEASE. OK.

Now.

I think here you get into the beautiful realm of what we writers like to call creative license. But let’s start with what you are for sure going to need to know:

• Check out this recently reblogged post for all you need to know onBlood.
• And let’s not forget that you are going to need to know the basics of how your killer’s weapon of choice actually kills. Is it poison? Gun shot?Sword? As the author you have to make sure you research it completely. If your killer can kill with a paper napkin, make sure you know what vein he cuts, and how much it bleeds.
• How to clean up after the murder is also essential to know. (Like, ok, I’m not going to Google “how to clean up after a murder,” no, go watch CSI.) If your character is competent, he or she is not going to leave behind fingerprints. How do they accomplish this? Gloves? Burning them off? Do they have bleach, to clean up the blood? How do they hide the evidence?

So, yes, there are certain things you need to know inside and out.

Alright, you say, but what about creative license?

You, as the author, are going to need to put yourself in the shoes of killer and victim. How they are feeling, what they are doing, etc. Approach it the same as writing any other scene—a good dose of imagination, a healthy dash of respect, let simmer. For example, I’ve never punched someone before, but I can pretty well imagine it would hurt for both parties involve, and can write it that way. I can picture the wind up, hear the crack of knuckle on bone. I’ve never personally experienced it, but with a little research, I can write it, and write it how I see fit.

• Alcohol and substance abuse

Children who are exposed to alcohol and substance abuse in the womb may suffer from serious birth defects. Small eye openings, retardation, a small head and brain and central nervous system issues are just some of the problems they could face, if they survive.

Growing up in a home where substances are abused can be even worse. ADHD, attachment disorders, doubt and feelings of inadequacy, depression and behavioral problems will be evident from a very young age. According to the FBI’s statistics, the childhood homes of more than 70% of serial killers experienced problems related to substance abuse. Be that as it may, there have actually been very few serial killers (relatively speaking) addicted to alcohol and substances – but many of them are known to have encountered such things in their youth.

• Psychological abuse during childhood

It almost goes without saying that most serial killers were abused as children. According to the interviews and discussions that have been held with known serial killers, emotional abuse and neglect has been the form of abuse most of them (50%) suffered.

They were humiliated often – and when parents meted out discipline, it was unfair, unpredictable, destructive and wicked. Even when a child is merely neglected, huge developmental failures can occur. The child will become desensitized; he will begin to believe that this emotionally barren world that surrounds it is something normal – and so he will grow up devoid of empathy for others.

Emotional abuse impairs a child’s self-esteem, and interferes with his ability to function adequately in society, succeed academically, and form healthy, intimate relationships. This is why we see that serial killers often fail to keep their jobs for any period of time and only rarely have successful relationships.

• ually stressful events in childhood

Accessible research material tells us violent ual events during childhood have serious adverse affects on an individual’s development. More than one known serial killer was forced to dress up as a girl as a form of punishment. The witnessing of violent ual acts between family members and/or parents had some of the most damaging effects.

Furthermore, some contracted venereal diseases as teenagers; were punished for ing as children; or were ually abused, most often by parents or family members. Such experiences in childhood will often create violent fantasies that continue into adulthood.

Childhood abuse leads to social isolation, learning difficulties (46% of serial killers never finish high-school), self-control issues and seizures. This research into child abuse serves as compelling confirmation that serial killers are made – not born.

• Bed-wetting

Even though bed-wetting in itself has been discredited as a predictor of later violent tendencies, it is speculated that it might be related to arson and animal cruelty in some way. Researches argue that persistent bed-wetting past the age of five is demeaning for a child, especially if parents or other figures of authority tease or belittle them about it. The child may then act out against animals or use arson to channel their anger and frustration. Over 57% of serial killers were bed-wetters until an unusually advanced age.

• Growing up lonely and isolated

Family members of future serial killers are usually out of step and at odds with each other. Their relationships are malfunctional and debilitating. These families also have a tendency to move around a lot, and the children are normally removed into shelters before they can turn 18.

It all boils down to the idea that such children have no meaningful relationship as they grow up, and therefore end up lacking the capacity to forge such relationship; they end up as “loners”. Serial killers are rarely remembered by classmates, as they rarely had any close friends. As they are frequently bullied by other kids, anti-social tendencies will also develop at an early age. A careful observer will see that this child starts dabbling in arson and theft, the use of dangerous weapons, hostility and aggression, and a complete disregard for others’ rights.

• Fantasies

Serial killers’ fantasies are often about control and violation. In fact, during research, it became evident that serial killers could remember NO positive fantasies they had as children. Some would fantasize about mutilating themselves or their s. They will even fantasize about their own traumas, over and over again – the difference being that in these fantasies they are the assailant.

Serial killers in the making will never discuss these horrid fantasies with anyone, but thoughts of fulfilling them will recur more and more frequently. Before the serial killer kills for the first time, the fantasies normally focus on committing the murder. Afterwards, the fantasies will focus on committing each murder more successfully, and with greater efficiency.

• Preferring auto- activities

Most serial killers admitted that during their teenage years they avoided parties and other social events. They definitely never experimented as normal teenagers do with ual activities among their peers, rather preferring ion and other auto- activities such as ography. In some cases there would be obsessive ion – as in the case of Andrei Chikatilo, who had awful scarring on his due to the aggression that accompanied his ion.

Without any substantial social structure in his life, the killer is unable to embark on a normal ual relationship, and thus is forced into solo ual activities. Certain forms of media, such as detective magazines, often have lurid tales of and murder that can also serve as an extra form of arousal – linking and murder together.

• Developing voyeurism and ism in adulthood

From an early age, many serial killers are intensely interested in voyeurism and ism as well as other paraphilias. Many will start their deviancy as relatively harmless peeping-toms, before moving on to house-breaking, , and murder. Given that elements of and dominance feature so strongly in most paraphilias, it is no surprise that this is often the route followed after adolescence.

• Acting out fantasies on animals

Almost all serial killers – in fact, 99% of them – admitted that they started by acting out their violent fantasies on animals before graduating to human beings. Due to the dysfunctional families most serial killers come from, such pathological and abnormal behavior may be ignored or completely missed – as in the case of Jeffrey Dahmer, whose father was unperturbed by the fact that his son was dissecting animals. These acts of animal cruelty are a great source of pleasure to young killers, and they manage to perfect the art completely – later performing the same acts on their human victims.

• Physical injuries

Head injuries received during accidents, repeated head trauma suffered during physical abuse or injuries during birth have been suggested as a very important link to aggressive and violent behaviour. Damage to the limbic brain, hypothalamus or temporal lobe may cause bouts of spontaneous aggression. These areas are involved with hormones, aggression, emotion and motivation; injuries to them may also result in seizures and forms of amnesia.

70% of serial killers received extensive head injuries as children or adolescents, clearly showing the link between these types of injuries and serial murder. Some researchers believe that the pre-frontal cortex (the area involved in planning and judgement) does not function properly in psychopaths.

 CREDITS: 

Since the resources for this I found were A-LOT, I'll post my credits for the two information above & then include some links to additional pages that could prove useful :)

• How To Write A Serial Killer - WritersHelpers
• Common Traits of Serial Killers - ListVerse

1. Female Serial Killers
2. Study Of Serial Killers
3. Serial Killer Quotes 
4. Working A Female Serial Killer Case
5. Criminal Profiling