General Question

sevenfourteen's avatar

What sets a serial killer apart from a murderer?

Asked by sevenfourteen (2419points) September 17th, 2009

I don’t really know what sparked this question but does a serial killer have to have a signature? Do they have to kill a specific amount of people? And what about a mass murderer, how come they aren’t serial killers… or are they? And last question, does anyone keep track of serial killers/mass murderers?

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42 Answers

dalepetrie's avatar

A serial is a series of events, a serial killer is a killer who kills on a series of different occasions. A mass murderer is someone who murders numerous people at the same time.

dalepetrie's avatar

In other words, if you kill a person on Tuesday, you’re a murderer, if you kill two people on Tuesday, you’re a mass murderer, if you kill one or more people on Tuesday and one or more people on Wednesday you’re a serial killer.

Lightlyseared's avatar

A serial killer is traditionaly a person who kills three or more people over 30 days or more with a cooling off period between murders and whose motivation is psychological gratification possibly sexual in nature.

Glow's avatar

This should help:

Serial Killer: A serial killer is a person who murders three or more people over a period of more than 30 days, with a ‘cooling off’ period between each murder, and whose motivation for killing is largely based on psychological gratification. (from wikipedia)

Murderer: a criminal who commits homicide (who performs the unlawful premeditated killing of another human being)

I guess you could say a serial killer is more of some one who commits a series of murders (3 being the minimum before its a series) and does so not because, Oh, lets say, the person said something nasty to them, but because they enjoy causing people either pain, or watching them die, etc. Plus, they usually plot it out. A murderer is the person who pulls out the gun and shoots the dude who said the nasty thing and usually never thought about it before doing it.

teh_kvlt_liberal's avatar

Dale got it
Don’t listen to anyone else

dalepetrie's avatar

@Lightlyseared and @Glow – you have both posted the wiki definition, but I dispute that, as far as I know, it doesn’t have to be 3 or more people, nor does it have to be more than 30 days, as long as they are separate events. There is also a “spree” killer who might just go on a killing “spree”. I think the reason they use the 30 day threshold is because most people who kill and then kill again in a short period of time usually are motivated by the same thing, like I just wanna go out and shoot people, maybe I get 3 Tuesday, 4 Wednesday and so on. A serial killer generally plans each murder as a separate event, making it a serial of events, and usually it takes time to plan these events…the often like to think about it. But it’s not impossible that a person could decide to kill someone, with the original intent of killing just that person, and they liked it so much they decided to do it again, and basically then got caught…that person would have been a serial killer, but might be labeled (incorrectly in my opinion) as a spree killer. I think the distinction is that a spree is a one time event stretched over multiple days. Mass murder is a one time event done in one occurrence, and serial killing is a series of unrelated events.

rebbel's avatar

@dalepetrie So, if someone kills a person in 2009, and then another one in 2014, and yet another one in 2020, what kind of killer would that make him?

Glow's avatar

@dalepetrie thats understandable. But I’m assuming that the reason they said 3 is because killing one person today, then another tomorrow is less common amongst serial killers and more of murderers, and that they are actually more likely to kill 3 or more.

But either way, its hard to put labels on things that deal with human emotions and behaviors. It’s just way too complicated because it can always be disputed.

SpatzieLover's avatar

Living in Wis, I feel like an expert on this one. A serial killer vs a murderer or mass murderer…The difference????
OBSESSION with DEATH! Obsession with seeing things die, feeling their skin, sleeping with them in bed or better yet, “loving” the dead so MUCH you take a head to work.

Yes, in the land of Gien & Dahmer I think I understand better than WIKI what a serial killer’s mentality is.

ubersiren's avatar

I’ve read a lot on serial killers, and so has my mom, for research purposes to help her write her novel. Anyway, I have always heard that it’s 3 or more people, too. Of course that can be debated, but I’m not sure 2 constitutes as a series. If you look up the definition of “series” at, it states that it means a number of thing in spatial or temporal succession. It’s hard to achieve that with only two incidents.

SpatzieLover's avatar

It has zilch to do with numbers and everything to do with mentality.

augustlan's avatar

Here is a page that details a serial killer I know personally. He was a friend of my ex-husband’s while they were growing up. He was in my house. Still freaks me out.

SpatzieLover's avatar

@augustlan luckily you lived to tell!

SpatzieLover's avatar

@augustlan Well written article on him

aprilsimnel's avatar

@SpatzieLover – Right? I grew up in Wisconsin, and I heard they just got another serial killer, Walter Ellis, a few days ago. :/

girlofscience's avatar

Speaking of which…


teh_kvlt_liberal's avatar

Dexter’s lab is back?!
TV puppet pals!

SpatzieLover's avatar

@aprilsimnel Yea, BUT they’re still claiming there’s no such thing as a smiley face killer…bastards! We watch the news each Nov 1st wondering how many more kids’ll have perished

charliecompany34's avatar

a serial killer has a pattern. he can be traced based on his behavioral evidence. a mass murderer is not a serial killer—he/she is one that has a certain cult following and/or he takes advantage of a moment or environment when a lot of people can be killed.

serial killer: john wayne gacy, jeffrey dahmer, etc. (patterns)
mass murderer: columbine, etc
cult mass murder: religious factions following one leader
(that sick reverend on an island that begins with a “G’ back in the day—it escapes me now, as well as dude in texas, was it david koresh?” flurtherites, help me out)

Buttonstc's avatar

There is one thing that sets serial killers apart. They are sociopaths.

A murderer (mass murderer or otherwise) may have been pushed to that extreme by a series of circumstances or it could be a crime of passion. Some of them may be sociopaths as well, but not necessarily.

Some of the lesser known kids involved in incidents where they shot multiple victims were definitely murderer but responding to constantly being picked on by others. Not saying that’s an excuse, but it doesn’t qualify them as sociopaths because many of them in subsequent interviews expressed sorrow and regret.

Another part of the question asked if there is anyone who studies them. The FBI has a unit designed specifically for that.

There was also a study done by the Secret Service on the cases of school shootings to determine if there were ways to prevent some of these scenarios. I believe it was either 20/20 or 60 Mins. which did a segment discussing this in more detail and the conclusions they came to were rather startling.

There is not much of anything that can prevent a serial killer other than killing them or locking them up for life since sociopaths lack any empathy or conscience.

Zen's avatar

About one more kill.

maggiesmom1's avatar

There’s a really, really good book written by a 20 year FBI serial killer where he talks all about what makes serial killers what they are, rather than mass murderers. It’s called Whoever Fights Monsters and I’d highly recommend it.

Zen's avatar

@ABoyNamedBoobs03 Nervous LOL

Now I’m a little scared of you.

ubersiren's avatar

@augustlan : Aaaahhh! So creepy… did he act strangely around you? Rockville… that’s way too close to me to want to believe it. :/

Dr_C's avatar

@charliecompany34 got it. The distinction is not based on the ammount of murders commited but rather the motivation behind them, as well as the specific pattern of each incident.

A serial killer (regardless of the ammount of homicides) will follow a specific and traceable pattern. A murderer (be it a single homicide or a mass murderer) will kill without any form of discernible pattern and without the psychological ramifications of carrying out the act in a specific way.

Girl_Powered's avatar

The number of times they make the front page seems to be one criterion.

dalepetrie's avatar

@rebel – a person even if they killed once every decade would still be a serial killer.

augustlan's avatar

@ubersiren No he didn’t act strangely at all. I didn’t particularly like him (he was kind of a lowlife who did a lot of drugs) but I certainly wasn’t afraid of him! We hadn’t seen him in a number of years by the time this happened. It was quite a shock, let me tell you!

ABoyNamedBoobs03's avatar

@Zen haha well it’s true. the serial killers are good at it, murderers are kind of messy about things.

mattbrowne's avatar


Darwin's avatar

All serial killers are murderers, but not all murderers are serial killers.

Murderer is a general term that covers anyone who kills another human being. The rest of the terms under discussion describe subsets of murderers.

rebbel's avatar

@dalepetrie I always read your answers with pleasure, because they make sense (to me) and esp. since they are usualy very long
—-Bit disapointed that i only got fifteen words…—-

I’m kidding, of course.
Thanks, i understand.

dalepetrie's avatar

I’m saving up my words for something special.

SpatzieLover's avatar

I’d say both this Petersen & this Petersen are serial killers even though the first “only” killed two, he had the evidence in his trunk that he planned to kill a third & possibly a fourth (the girlfriend and her child most likely would’ve been the next victims of this sociopath)

Darwin's avatar

So is a sociopath who kills only one or two people before he is caught the same thing as a serial killer, who is a sociopath who has killed a number of people before being caught? Or does a serial killer actually have to take out a certain number of people in order to be a serial killer? How many events does it take to form a series? Does it matter if one is related to the victim(s) or do true serial killers typically go for folks they don’t know but who match some criterion that they use?

Bear in mind the word “serial” is derived from “series” and means arranged in a series; consecutive, sequential;.

Inquiring minds want to know!

Buttonstc's avatar

I’m not sure how many authorities insist upon in order to be classed as a serial killer.

And I don’t know that it’s a matter of numbers at all in it’s essence. A murderer and a serial killer could have the exact same totals ( whether that be few or many) and it doesn’t speak to the main issue germane to the classification.

There are many different types of people who, given the right
set of precipitating circumstances, would be capable of murder. But it takes a distinct type of mind to repeatedly plan and carry out the cold blooded killing of others time and time again. Someone totally devoid of empathy or conscience who even takes pride in these acts, essentially a sociopath. I think this is what prompted law enforcement to create this category and ” serial killer” is what they agreed upon as a common name.

They had to describe this category in some way because most other murders are committed by someone known to the victim ( not every single one but def the vast majority) so there is a methodology to determining who it would be.

With a serial killer, all that goes out the window and a different approach is called for.

So, I would presume that the exact number is less important to the classification.

SpatzieLover's avatar

Is anyone else watching 20/20 tonight? Looks like you don’t actually have to be a murderer to be a serial killer according to some. This scum-bag preyed on women & infected them with HIV

SpatzieLover's avatar

@teh_kvlt_liberal HA! He DOES look like Emo!

Darwin's avatar

The books are better than the TV show.

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