Most people don’t just disappear. They leave something behind— a call, a message… a reason. Lizzi always made sure of that. She never left anyone guessing. Until one night… she did. She walked out to meet a friend— someone she trusted—and promised she’d be home by midnight. But she never came back.
And what actually happened that night—wasn’t random. It wasn’t a stranger. It was planned. And it started with someone Lizzi thought was safe. [intro] Elizabeth Marriott—known to everyone as Lizzi—was born in Westborough, Massachusetts, in 1993. She had a clear plan for her future. Lizzi wanted to study marine biology—she loved sea life, and she wanted to build a career around it.
After graduating from Westborough High School in 2011, she moved to New Hampshire to attend the University of New Hampshire. And if you asked anyone who knew her, they’d all tell you the same thing. Lizzi was kind. Easy to talk to. The kind of person who made people feel comfortable almost instantly.
She was always smiling—always bringing energy into whatever room she walked into. She loved meeting new people. Sometimes a little too much. At the time, Lizzi was living with her aunt and uncle in New Hampshire, while her parents remained back in Massachusetts. And when Lizzi moved in, the house changed.
It felt brighter. Lighter. Like everything just had a little more life to it. Her aunt and uncle loved having her around, and they couldn’t have been happier to have her living with them. Well, she quickly settled in—getting a job at Target, while also volunteering at the New England Aquarium in Boston.
Even at work, people noticed how cheery she always was. She was personable, outgoing… the kind of person who went out of her way to make others feel welcome. Lizzi was also in a relationship with a woman named Brittany. Everything about her life felt like it was moving forward. Steady, normal and safe.
But that trust— that openness with people— would end up putting her in the path of someone who saw her very differently. And in October of 2012…Lizzi Marriott vanished. LIZZI GOES MISSING It was October 9th, 2012, and the day was pretty normal for Lizzi. She had classes in the evening and then she wanted to go and meet a work friend. Pretty standard stuff. So, she attended her classes, and then she texted her girlfriend, Brittany, about going to meet up with a friend at her apartment in Dover.
Not only this, but she had also told her aunt and uncle that she was meeting this friend. So, it wasn’t anything last-minute or secret. She left a note for her aunt and uncle at the table in her signature handwriting that she was out and that she would be back at around midnight, give or take.
Now, Lizzi had a decent social life, but that didn’t mean that she was the type to not inform anyone where she was going. She would always let her aunt, uncle, friends, and parents back home know where she was going. So, her aunt and uncle thought nothing of it. But midnight came and went, and October 9th turned to October 10th, but Lizzi didn’t return home.
When her aunt and uncle woke up, they were shocked to not find she wasn’t at home. She wasn’t in her bedroom; her stuff was untouched, and to their surprise, they found out that she had not made it to work. She had a shift at Target in the morning, and then her classes would be held in the evening and night, but Lizzi hadn’t made it to work, which only made her loved ones more concerned.
She also hadn’t reached out to Brittany or even her parents since last night, and this was really weird. Brittany and everyone else were starting to get this sinking feeling, and they just knew that they had to involve Lizzi’s parents and the police quickly. This was not like her.
She wouldn’t just skip work and not call or text anyone for such a long stretch of time. Luckily, the police also took serious note of 19-year-old Lizzi’s disappearance and immediately reported her missing and began the search. Her parents also made the two-hour drive to New Hampshire, and they immediately started asking people everywhere.
A reward was put up for any information or leads, and they looked everywhere they could think of. Meanwhile, the police had a lead of their own. They knew that Lizzi was going to meet a friend, and with the information they had at the moment, this friend might have been the last person to see or interact with Lizzi. THE INVESTIGATION Finding this friend of Lizzi’s was easy for investigators.
Everyone knew who it was. It was a woman by the name of Kathryn McDonough, and she was not only Lizzi’s friend but also her coworker at Target. See, Lizzi had just recently started hanging out with Kathryn. And being the friendly and approachable person she was, made friends with everyone.
Kathryn had invited Lizzi to her apartment in Dover. The plan was to have dinner, kill some time, and run some errands. Well, the police had a little chat with Kathryn, and according to her, Lizzi never showed up. Now, Kathryn was kind of bummed about it to be honest. She invited Lizzi to her home, and she waited and waited, and then she was a no-show. This caused Kathryn to go run errands on her own.
For investigators, this was just yet another dead end. They felt for sure that Kathryn would’ve had something for them – literally anything to tell them where Lizzi had gone… but she was just a stumped as they were. So they were snet back to square one. Now, the police were truly baffled by this point, so they even called in the help of the FBI at one point.
See, the thing is, even if they couldn’t track down Lizzi, at the very least, the police wanted to find her car. She had driven it to go and meet her friend, so surely her car would have some clues. But her car had vanished just as mysteriously as Lizzi had… so this was much easier said than done. But the police doubled down on this search for Lizzi’s car, and before long, they managed to find it. It was in a very peculiar place.
See, her car was found abandoned in the parking lot of the University of Durham. This kind of corroborated Kathryn’s version of events. So did she not even go to Dover to meet up with Kathryn? What was she doing at the University of Durham? And most importantly, where was she when her car was… well… here, of all places? The police did ask her parents, relatives, and friends if she knew anyone at the University of Durham, but they were all confused. She didn’t know anyone who went there, as far as they were concerned.
So, what was her car doing in a place far away from where she was supposed to go? The police, and everyone else, needed answers because time was running out and Lizzi was still missing. THE PLOT THICKENS After finding Lizzi’s car but not Lizzi, the police then looked at her phone records and her location.This was a key piece of evidence in her case.
According to her phone location, Lizzi was in the Dover area at around 10 pm or a little after that. Now… this was weird. According to Kathryn, she hadn’t seen her that night because she “never came” to Dover, but now, her phone location data was saying something else entirely. The police also searched nearby bodies of water and used advanced sonar and camera technology to find something—anything—that could lead them in the direction of solving Lizzi’s case. But still… nothing turned up.
The police were now highly suspicious of Kathryn at this point, thanks to the new revelation about Lizzi’s phone location. They just weren’t able to find anything incriminating against her yet. Well, that was until some time passed and an arrest was made. But it wasn’t what you thought. Kathryn was not the one arrested.
It was a 29-year-old man. His name was Seth Mazzaglia. But it wasn’t like Seth was just some stranger – no, he and Kathryn actually knew each other very well. Seth was Kathryn’s boyfriend. And according to him, he was also present that night at the apartment with Kathryn. Contrary to what Kathryn had been pledging all this time, claiming that Lizzi never showed up at her apartment in Dover, Seth had something else to say. According to Seth, Lizzi was at the apartment the night she went missing.
But what was going on now? Who’s lying and who’s telling the truth? And if Lizzi was at the apartment like Seth said, where was she now? Well, this was where things took a very dark turn. See, Seth was also a graduate of the University of New Hampshire, just like Lizzi, and he had actually studied theater.
He was also a martial arts instructor and had a black belt in karate. But there was something darker, more twisted about Seth that he only showed to people close to him—like his partners. Seth was someone who exercised and asserted control behind closed doors, and he liked meek and submissive partners.
Kathryn knew about this, and a quick look into Seth’s internet history proved that the adult websites he liked to visit… well, they proved that these were his desires as well. He went by the alias “DarkKaiser” on these websites, and it was safe to say that things were very disturbing. And by the way, the name Dark Kaiser… well, in German, Kaiser translates to “ruler” or “emporer”. Some may even translate it as “dominator”.
Now on top of all this, it was reported that Seth was violent and abusive with his intimate partners. One of Seth’s ex-girlfriends later came forward and stated that Seth would turn into someone else if his needs weren’t met. Basically, Seth was someone who thought that women were obligated to give him whatever he wanted, whenever he wanted, and however he wanted it, and if, God forbid, she declined for whatever reason, then Seth would turn violent and resort to force. So… this was Seth.
Now, Kathryn was his current girlfriend, and the two had visited various adult websites looking for another submissive partner to play out their fantasies in the bedroom. Now, considering Seth’s past, we don’t know if Kathryn was fully a willing participant in all this, or if Seth was forcing her hand… but the facts are the facts – and both she and Seth had been visiting these online chat rooms to try to find, best I can gather, a third person to bring into their bedroom.
But I’m getting ahead of myself. See, by now, the police finally arrested Seth and Kathryn both, and they questioned them separately. This was when Seth told the police that Lizzi was at their apartment. According to Seth, in the beginning, everything was fun. The three watched a movie, talked, and then engaged in a game of poker.
Then, out of the blue, Seth suggested that they get intimate with each other, which they did; But it was during this act that something happened and Lizzi… well, she lost her life. Seth didn’t explain what happened exactly. He just told the police that one moment, Lizzi was alive, and the next, she wasn’t.
Now, this really scared Kathryn and Seth, and they decided to get rid of Lizzi instead of calling the police so that the crime wouldn’t be pinned on them. How they came to this conclusion is beyond me. But anyway, when Seth and Kathryn realized what had happened—or should I say what they had done—they decided to dispose of Lizzi and do their best to cover their tracks.
So, they took an unresponsive Lizzi to Pierce Island and tossed her into the Piscataqua River and then abandoned her car at a random university parking lot and drove away in the dark. If the police were shocked before, they were officially stunned now. Seeing Seth describe the whole scene without any emotion or remorse… was very hard to digest.
It was like he was just recapping a movie he saw last week. Nothing about his demeanour seemed to suggest that he’d just taken someones life… but that’s exactly what he had done. But the police now knew something that was very devastating. Lizzi was gone. She wasn’t going to be found alive or… well, found at all.
See, the Piscataqua River is huge, and Lizzi’s remains… they could be anywhere by now, if they even still existed at all. Even though the police knew that it was likely a lost cause, sent out teams and divers to search for Lizzi following this confession, but they were unsuccessful in recovering her.
This was a huge blow to her loved ones. The fact that she was missing was hard enough… but now this? It was almost too much to bear. But… it was safe to say that the police didn’t believe all that Seth was spewing out of his mouth. Now they believed that he did murder her, but it was no accident.
The police were sure, given Seth’s violent history with women, that something bad had happened in that very apartment. But they believe that it was intentional. Because get this, on the night Lizzi was at the apartment, neighbors of Kathryn and Seth heard a woman’s loud screams. This obviously didn’t amount to something pleasant that accidentally went wrong.
Whatever happened in that apartment was really tragic. The police just needed to find out exactly what they were missing. And they did. On Seth and Kathryn’s phones. What they found on their phones… it was life changing. A DEADLY GAME OF POKER While the couple was behind bars and the police now knew for sure that Lizzi was not coming back, they built their case because this couple was due to stand trial.
They had given different versions of their stories, and without boring you with the irrelevant details, both Seth and Kathryn stressed that the relations between the three of them were consensual, and Lizzi just tragically lost her life as a result of an accident during the deed. But here’s the thing, text messages between Seth and Kathryn told an entirely different tale, and it was really disturbing. The part about Seth’s and Kathryn’s fantasies was true.
They were always actively looking for partners to play out their fantasies in bed. But this time around, Seth wanted Kathryn to bring a friend of hers for a different experience. Basically, Seth wanted to engage in relations with Kathryn’s friend while she would sit and watch everything go down.
Now again, we don’t know if Kathryn was totally fine with this, or if she was being forced to do this… but what happened, happened. So, abiding by Seth’s request, Kathryn suggested none other than her new work friend, Lizzi Marriott. But here’s the thing – Lizzi knew nothing about this arrangement. She was in an exclusive relationship with Brittany, and as far as we know, she wasn’t one to push boundaries. She was perfectly fine with her relationship and the course they were on.
So, when Kathryn “invited” Lizzi to her apartment for a fun night in, Lizzi really thought that the two were going to be alone at the apartment and were going to have a movie night or something. But we all know by now that Kathryn’s invitation was anything but tame. Kathryn didn’t even bother to ask Lizzi about the fantasy they were about to engage in.
SHe just thought by default that Lizzi would agree to do anything since they were friends. All of this… is just so hard to wrap your head around. But… well… here we are. So Lizzi arrived at the apartment, and she got her first surprise of the evening when she realized that Kathryn’s boyfriend was also joining them.
Now, she didn’t think much of it, because initially, Seth didn’t give off any creepy vibes. The three sat down, and they watched a movie, but somewhere in between, the three started to play poker, and a rule was enforced in which the person who lost each time would lose a piece of clothing. But the thing is, Lizzi was not very good at poker, she was obviously losing, and this was when Seth suggested that Lizzi and Kathryn… well… Lizzi drew a line right then and there.
But with Lizzi’s refusal, Seth was quietly stewing, but he didn’t do anything immediately. But after a few moments, he just quietly got up, went to his room, grabbed a rope and gloves, and then came back to the living room, where Lizzi and Kathryn were. Seth sat down behind an unsuspecting Lizzi, and when she least expected it, he made his move. He bound Lizzi, did what he wanted to her… and all the while… Kathryn just watched.
I can’t even imagine how Lizzi must have felt seeing her friend just sitting across from her and doing nothing to stop this. She just sat there, staring, watching the worst night of her friend’s life unfold in front of her eyes… and did nothing. Well, once the police got the whole story pieced together, they searched the apartment, which was a mess by the way, and they managed to find clothing belonging to Seth with his and Lizzi’s DNA on it. But things were about to get even wilder.
See, after ending Lizzi’s life, Kathryn and Seth called up some of their friends to help with the cleanup. Just called them up for help like it was a casual Tuesday and they needed a hand moving a couch. But two people, Roberta Gerkin and Paul Hicock, came to the apartment, and they saw what Seth had done.
According to the two, Seth claimed that “this time, things had gotten too far” because he “blacked out.” Luckily, the other couple didn’t participate in disposing of Lizzi’s body, but they also didn’t call the police either. They just instructed Seth and Kathryn to call the police and left the apartment, not involving themselves in this mess.
And I mean,, good on them for walking away… but they should’ve called the police themselves. Now, this is no one’s fault besides Kathryn’s and Seth’s, but if only Roberta and Paul had called the police, this case would’ve been solved much quicker, let’s just be honest here. But that didn’t happen.
When Kathryn and Seth realized that they were going to have to deal with Lizzi themselves, they hid her in a suitcase, drove her car to Lake Piscataqua, and dumped her body in the water. They then proceeded to abandon her car at the University of Durham parking lot to throw the investigators off, and then they also got rid of all the evidence by throwing it in dumpsters.
This ordeal took them hours, and they finally reached home at around 6 in the morning on October 10th. According to Kathryn, Seth was very excited and pleased with what he had done. He had no remorse… this man was actually proud of himself. This whole thing… its just haunting.
To think that Seth and Kathryn would go this far to play out their fantasies and target an innocent woman who wanted no part in any of it… THE SENTENCING At the trial, the prosecution laid everything out. They even showed letters in court written by both Seth and Kathryn, and in these letters, the two had plans of running away to a country with no extradition treaties, but not before taking care of Roberta Gerkin and Paul Hicock—the only witnesses of the crime.
It is seriously so scary to think that these people didn’t even stop to think about their actions. All they wanted was to get away with murder – even getting rid of the sole witnesses. At trial, Kathryn did pull out the manipulation card. She told the court that it was all Seth and she was forced to act on everything he ordered her to do because she was scared for her life.
See, Kathryn had gotten into a serious relationship with Seth when she was only 18 and Seth was 29. So, it is safe to assume that Seth manipulated and brainwashed Kathryn when she was younger, but still, it doesn’t take away the fact that Kathryn was a willing participant in all of this. Just because you’ve been led astray, that doesn’t mean that you don’t have to work out redemption.
But Kathryn claimed that Seth controlled everything that she did, and she was forced to cut off all contact with her parents. Now, this was extremely heartbreaking for her and her family both, and it shouldn’t have happened to her, but she had so many moments in which she could’ve stopped this crime from happening – and that’s the real purpose of this whole trial.
In terms of Kathryn being led off course by this man… that’s a story for a different day. All that matters right now is that, whatever the path she took, Kathryn ended up where she did. And now Lizzi had to pay for it with her life. Now let me be clear – I know good and well how difficult it can be to speak up against an abusive partner. I’ve seen how that plays out in real time. Fear as an astoundingly powerful motivator.
But the fact that Kathryn willingly brought someone else into this mess – knowing who Seth was and how he was likely to behave… that is a violation unlike any other. She could’ve saved Lizzi. She could’ve done something else, she could’ve stepped up.
She could’ve at least tried to convince Seth to find someone willing to help act out on these fantasies. But, she did none of that. She just went along with it and watched as her boyfriend murdered her friend, without so much as a single word against him. Kathryn was just as involved as Seth, she could’ve even gone as far as, I don’t know, not asking Lizzi to come over that evening, and making up a lie and telling Seth that Lizzi was too busy. But she didn’t. She facilitated her friend’s murder.
Well, in July 2013, Kathryn agreed to plead guilty to hindering prosecution, conspiracy, and witness tampering in exchange for testifying against Seth at his trial and in exchange for a lighter sentence. And when I say “lighter sentence,” I mean it literally. She was given a whopping one and a half to three years in prison.
Lizzi’s family was not happy with this at all. She practically laid out a trap for Lizzi to walk into and lose her life. Lizzi trusted Kathryn wholeheartedly, but look where that got her. Needless to say, her parents and loved ones expressed their disdain with very strong words, and understandably so.
The judge also directly addressed Kathryn and told her that she was a major reason that Lizzi is not among her loved ones today. Not the sole reason… but she was a major driving force. But less than a year later, Seth’s trial was held. His defense tried to pin everything on Kathryn, which is always a classic move, and the star witness of this trial was none other than Seth’s own girlfriend, Kathryn.
She testified against him, and the prosecution presented heaps of evidence, including DNA evidence, his violent history, and his tendencies with women. It was an open and shut case for the jury. The verdict was out, and Seth was guilty of the first-degree murder of Lizzi Marriott. Seth was given life in prison without the possibility of parole, and he will stay behind bars for the rest of his life. Kathryn, on the other hand, was released on parole in 2016.
This case… is just even more painful to think about because Lizzi’s body was never found. To this day, the police and volunteers have been unsuccessful in finding Lizzi’s body. Her family is unable to say goodbye to her or lay her to rest, and somehow, this just intensifies their pain ten times more.
Lizzi always wanted to become a marine biologist, but she never got that chance. But in her wake, her family has established the Lizzi Marriott Intrepid Explorer Fund, which allows students to pursue Lizzi’s dream and do all the amazing things Lizzi was destined to do. You know, what’s particularly haunting is that Proverbs 1 almost literally gives a play-by-play of this case. It says, “If sinners entice you, do not consent.
They will say, ‘Come with us, let us lie in wait for blood. Let us ambush the innocent without reason. Let us, like Sheol, swallow them alive.’” But later adds “Do not walk in the way of them. Hold back your foot from their paths, for their feet run to evil and they make haste to shed blood.” But James 4:17 tops this off perfectly by saying, “Whoever knows the right thing to do and fails to do it… for him, it is sin.”
