A Woman Hell-Bent On Revenge | The Jennifer San Marco Story

(Jennifer San Marco. Picture credit: NBC News)

A smile can be so deceiving, don't you agree? The picture above looks like a nice, friendly woman in her 40s, probably someone's mother? how wrong can we be sometimes when we look at someone and think that they could never be capable of carrying out mass murder. Oh yes, the lady in the picture before you is an American mass-murderer and her name is and was Jennifer San Marco. 

As you know, I have covered various cases on this blog but this is the first time I have written about a female mass murderer who, to coin the term 'went postal' at her former place of employment. 

So let me tell you more about this case with a little bit of background first...

Jennifer came into this world on the 6th of December 1961 full of promise, she was born in New York and attended the same school in Brooklyn as Adam Yauch (better known as a member of the world famous Beastie Boys) and actress Marisa Tomei. Jennifer was shy and kept herself to herself and was described as a friendly girl but little was known about her home life. As she blossomed into a teenager and attended college and University, all seemed to be fairly normal, no traumatic incidences or strange behaviour, no red flags popped up anywhere, she seemed to have the world at her feet but she dropped out of University and didn't graduate for unknown reasons (but you will see as you continue reading that this was the beginning of a pattern for Jennifer).  

Through her 20s and 30s, Jennifer had undertaken a variety of different jobs from working as a guard at a medium security prison to working as a police dispatcher (I just want to include here that Jennifer had undertaken various psychological examinations for these roles and passed with flying colours) and everything in between. There was a constant pattern emerging of her quitting jobs for unknown reasons but nothing too dramatic. She finally found a job where she stayed for quite a while (6 years) as an employee and this was a postal clerk position. For some reason this seemed to be the role that she had stuck at until things started to take a sinister turn. 

Jennifer's behaviour in and outside of work was beginning to raise a lot of eyebrows and in the case of her neighbour, Beverly Graham, it caused a number of heated arguments. Jennifer was not drinking or taking drugs but her behaviour was spiralling out of control and it seemed to have come out of nowhere. She would stand in front of her neighbour Beverly's house and sing and shout at all hours of the night. Nobody knew why she was doing this but Beverly was sick and tired of it and the two women did not get on in the slightest. 

Her colleagues at the postal plant in Goleta, California were getting fed up of her antics at work too. She would often be seen talking and arguing with herself and she would mumble racist remarks under her breath, it was creating a terrible atmosphere at work but everyone just tried their best to ignore it until one day she completely flipped out and hid underneath one of the machines. 

The whole scene was that chaotic with Jennifer shouting and acting like a woman possessed that her colleagues were too scared to be near her and the police had to be called. When the police arrived they had a hard time trying to get her to come with them with legs and arms flying all about the place, there was only one place to take her and that was to the nearest psychiatric hospital. 

Jennifer spent three days there and was soon released and spent some time on sick leave from work before returning several months later. However, when she returned it was as if she had gotten worse, not only did she look very unkempt but she was even more aggressive and the ranting and raving continued, the managers themselves had to escort her off of the premises and she was told never to return. The postal company decided it would be best to retire her early due to her declining mental health. Jennifer was very bitter about the whole situation because to her she had done nothing wrong, she was convinced that everyone was against her. 

What she was going through sounded a lot like Paranoid Schizophrenia however I cannot find any public record of her ever being formally diagnosed with this or what her psychological diagnoses was. She had the ability to manipulate those around her. There would also be moments when she could hold a normal conversation and then the next minute she would be rambling and indulging in strange behaviour. 

After being retired from her role at the postal facility, she moved to New Mexico. One would hope that this would have been a fresh start for Jennifer but she continued to decline. She would bounce from having ideas of having her own business to kneeling at the side of the road praying. She tried to register for a publication which was viewed as racist as well as becoming obsessed with launching her own car food company. When these two ventures didn't materialise she sank deeper into madness and paranoia and became fixated on the past. 

Jennifer (44) was an injustice collector and with so much time on her hands there was nothing else left to do but sit and stew on those she thought had wronged her over the years. 

Her behaviour in New Mexico continued to be bizarre, she would often spit in public, would be seen praying and mumbling to herself and once went to a gas station and took all of her clothes off. She would also sit and stare at people, She made a lot of people feel uncomfortable and her appearance was very off-putting with clumps of her hair missing as she had cut it herself and her clothes were dirty. She was seen one day, praying at her car and when a passer-by asked if she was ok, she replied ''They pray before they go in''. 

Jennifer would spend hours in her New Mexico home rambling and writing endless notes that were later found by investigators. She became convinced that her former colleagues at the post facility, her old neighbour Beverly, the police department and one of the psychiatric facilities she had been attending, were all working together in a plot to ruin her life. She obsessed over this and that obsession soon became a determination, a determination that they would all pay for what she thought they had done to her. 

So she set about planning her act of revenge and went to two different pawn shops in New Mexico, one to purchase the gun and the other to purchase ammunition. For the gun she had to fill in an application form and the whole process took about two days before she was able to collect the gun. Surprisingly, she was able to get through the application process fine, one can only assume that she had given false information. 

She now had her plan and her weapon and on the night of the 30th of January 2006, she got into her car and the first person who was going to pay the price in her mind, was Beverly Graham. The two women had not seen each other in a long time but Jennifer had been storing up all this anger inside for quite some time. 

I'm sure we've all had neighbours we didn't get along with or jobs that we hated or were fired from, but those of us with a healthier state of mind move on, Jennifer could not. She shot and killed Beverly Graham that night. The neighbours later told police that they heard the shots ring out between 7:15 pm and 8:15 pm. 

As soon as she had killed 54 year old Beverly she got right back into her car and made her way to the postal facility. The number of people who actually worked in that building was approximately 300 but on this particular night only 80 were on that shift. 

Knowing that there was no way she would be able gain access so easily, she followed on the tail of another vehicle through the company gates. Without missing a beat she jumped out of the car and threatened an employee at gunpoint for their ID badge. 

As soon as she got the ID she let the terrified person go and continued on with her planned rampage. Once inside she shot six people, one person was just barely hanging onto life and actually died later in hospital. When the other employees heard the gunshots they ran out to the street and across the way to the local fire station. 

Eventually Jennifer San Marco turned the gun on herself.

As to her motive for this horrendous murder spree, people have their theories. Some believe she was simply ill, paranoid and believed that people were out to get her. Others believe that she was motivated purely by racism. Jennifer was white and her victims at the facility were all, as the police said 'minorities'. Three of the victims were African-American, One was Filipino, another was Hispanic and one was Chinese-American. 

With the 6 victims at the postal facility, the ex-neighbour Beverly who was murdered and then Jennifer herself, that brought the total to eight people who lost their lives that dark January night back in 2006 and what for? Theories remain as to why she did it, people could blame the authorities for not seeing the red flags quicker, they could blame the police, fingers could point in all directions but the fact remains, Jennifer San Marco was a cold blooded killer and she was mentally ill.

People say there was no signs in her childhood as to what was to come but was that really the case or did they turn a blind eye to certain things? We will never know. Some people believe she was totally fine but had a breakdown or had a knock to the head that changed her. We do know that she drifted from job to job and had a habit of walking out of them.

This horrible case has gone down in American history as one of the deadliest mass shootings. It brings my memory back to a case I covered in 2019, the James Huberty case otherwise known as The McDonald's Massacre. Here was another individual who had mental illness and went on a mass shooting at a McDonald's restaurant, which has also been included in that horrifying list of America's deadliest mass murders. 

2006 doesn't feel that long ago and if you think about it, it actually isn't, for this to have happened at a time when we thought that we were getting tougher with gun applications, security and had made some improvements with mental health support, it is very frightening. 

I'm thinking of the victims and their families, all those people did was go into work that night to try and make some money to pay bills and put food on the table for their children, their families, they didn't deserve what happened to them and neither did Barbara. 

May we pause to think of them...

Barbara Graham (54)

Ze Fairchild (37)

Maleka Higgins (28)

Nicola Grant (42)

Guadalupe Swartz (52)

Dexter Shannon (57)

Charlotte Colton (44)

(From left: Beverly Graham. Charlotte Colton, Dexter Shannon, Maleka Higgins, Nicola Grant, Guadalupe Swartz, Ze Fairchild. Picture credit: Denver Post)


  1. Good evening Jo. Brilliant work !
    I agree with the picture, she didn’t look like a killer.
    Oh my god, she was pure evilness ! It’s such a shocking mass murderer case.
    RIP to all the victims of this sick woman. She was indeed mentally ill but a cold mass murderer killer. My thoughts are with the victims and all the relative & family members of the victims.
    Thank you so much for your amazing work Jo, I will definitely check all the links as always.

  2. These stories always scare the hell out of me. Here in Connecticut we had a similar circumstance happen at the HDI Beer Distribution plant in Manchester. It's inexplicable and confounding when you see someone with such anger and mental instability acting out on these emotions and anger. The people that lost their lives that night leaves one speechless and heartbroken. As horrific as this was it's a fortunate circumstance that more people weren't at work that night and I can only imagine how much this effected the people that survived this tragedy. Families lost loved ones and coworkers lost friends that they worked with, truly devastating.

    Brilliant writing and an incredible story, my thoughts go to everyone affected by this tragedy.

    1. As always, thank you for taking the time to read and comment. I always look look forward to hearing your thoughts on my posts, always detailed and you can tell that you really empathise with the victims and families. You understand my writing so well and never rush your comments, they are carefully thought out and considered. I appreciate your words and support on all of my posts. I thank you too for your requests.