REOPENED: Mr. Big Sting

Summary

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Cold Case Files: REOPENED – "Mr. Big Sting"

Podcast: Cold Case Files
Host: Paula Barros (voice talents include Doug Dupe, investigators, and witnesses)
Date: September 4, 2025
Case: The 1992 Murder of Marie Dupe, Cape Breton, Nova Scotia

Episode Overview

This episode of Cold Case Files investigates the 1992 murder of Marie Dupe in Cape Breton, Nova Scotia, a case that confounded investigators for nearly a decade. The episode details the painstaking investigation, complicated by harsh winter weather and rumors, and the eventual use of an elaborate undercover operation known as the "Mr. Big" sting, which elicits a confession from the perpetrator, Ernest Gordon Strowbridge.

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Key Discussion Points and Insights

Setting and Victim Background

• Cape Breton Setting: The episode opens with a vivid description of Cape Breton's natural beauty, traditional music, and close-knit community ([00:05]).
• Marie and Doug Dupe: Recently retired to Cape Breton, seeking a slower, peaceful life ([00:48]–[01:00]).
• Marie's New Job: Marie, growing bored in retirement, takes a job at the local Big Bend convenience store ([01:00]–[01:33]).

The Crime and Initial Investigation

• The Night of the Murder: On March 21, 1992, Marie works her first night shift during a blizzard. She is murdered during her shift ([01:33]–[02:34]).

• Discovery: A local man finds Marie alive, but critically injured, lying in blood at 4am ([02:34]).

  • Sergeant Jim McLean:

    "I walked down to the back of the store and I could see that this lady was brutally stabbed. Her throat was slashed, the side of her face was slashed, her right ear was severed right off. She had blood, it seemed to me, coming out of everywhere. I was horrified." ([02:34])

  • Despite efforts, Marie dies an hour later due to blood loss.

• Crime Scene Challenges:

  • The blizzard ruined potential footprints or tracks outside.
  • Melting snow inside the store compromised evidence, mixing water and blood ([03:18]–[03:32]).
  • Key Evidence: Multiple cigarette butts collected for future DNA analysis ([03:41]).

Early Suspects and False Leads

• Doug Dupe Investigated: Doug is initially a suspect, especially after his resigned comment on seeing the police ([04:20]).
  • Doug Dupe:

    "Right off the bat I says, 'My wife did. What else could be the bad news?'" ([04:20])

• Community Rumors: The investigation is muddied by unfounded rumors of drug dealing and “mafia ties” ([04:57]).

Evidence and Witness Testimony

• Discovery of the Knife: As snow melts, the bloody knife used in the murder is discovered outside the store ([06:12]). It was a store sandwich knife stained with Marie's blood.

• Store Receipts and Witnesses:

  • Police track every transaction from Marie’s shift, interviewing customers ([06:51]).
  • One significant, unidentified sale at 3:16am for cigarettes.
  • Witness at 3:18am:
    • Customer describes a man acting strangely—statue-like, unresponsive except to smoke or sip coffee. He deeply unsettled the witness and Marie ([07:22]).
    • Sketch generated, noted for the suspect’s “dead” and “deep” eyes ([07:45]).

Case Goes Cold, Then Heats Up

• Years of Investigation: Despite hundreds of interviews, police cannot locate the man matching the witness sketch ([08:26]).
• DNA Breakthrough:
  • In 1997, DNA testing capabilities allow the cigarette butts’ DNA profile to be uploaded to a national database.
  • In 2001, a match is found: Ernest Gordon Strowbridge, who lived nearby at the time and has since moved ([08:56]–[09:12]).

The Mr. Big Operation

• Need More Than DNA:
  Detective Glenn Bowmaster:

  "All the DNA did was put him in the crime scene. It's a pretty big stretch from putting someone in the crime scene to saying he committed the murder." ([09:33])

• Undercover Sting:

  • Police use the "Mr. Big" technique: Strowbridge is drawn into a fake criminal gang and ultimately meets the “boss” (Detective Bob Deasy) ([10:31]).

    • Setup: Strowbridge thinks he’s interviewing for a role in a crime family; must confess a serious crime as a sign of loyalty ([11:00], [11:42]).

  • Confession:
    Strowbridge confesses openly:

    "There was a thing called the big Benz murder... It was a convenience store... I didn't realize I'd done it until, like, the next day because I blacked out. And then when I woke up next day, I was covered from at the toe and black... There was a murder there. Yeah. And I done it." ([11:52])

  • Detective Deasy’s Reaction:

    "That really took me aback. And I then had to think backwards from that point because essentially we began with the climax." ([12:43])

  • Strowbridge (on why he confessed):

    "The only reason why I told you is because... you know, it's part of the trust. Trust relationship part. I appreciate that." ([13:21])

Arrest and Resolution

• Strowbridge Arrested: He is then confronted by Detective Doyle, who informs him everything was taped.

  • Strowbridge soon admits the truth in the police interview, expressing some regret ([13:32]).

• Legal Outcome:

  • Strowbridge pleads guilty almost a year later. As he was a juvenile at the time, he receives a life sentence with a possibility of parole in seven years ([15:18]).

• Doug Dupe’s Reaction:

  • Doug Dupe:

    "No, it's not enough. No. He did his first 12 years not being caught. That was his parole. Guy should be doing life right now. But I'm glad it was before I went to my grave myself because it's nice to see it settled." ([15:55])

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Notable Quotes & Memorable Moments

• “Her right ear was severed right off... I was horrified.” — Sgt. Jim McLean ([02:34])
• “All the DNA did was put him in the crime scene. It’s a pretty big stretch… to saying he committed the murder.” — Det. Glenn Bowmaster ([09:33])
• “I didn’t realize I’d done it until, like, the next day because I blacked out.” — Ernest Gordon Strowbridge ([11:52])
• “The only reason why I told you is because... it's part of the trust.” — Strowbridge ([13:21])
• “Guy should be doing life right now. But I'm glad it was before I went to my grave myself.” — Doug Dupe ([15:55])

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Key Timestamps

| Timestamp | Segment | |-----------|-------------------------------------------------------------------| | 00:05 | Introduction, Cape Breton background | | 01:33 | Marie Dupe’s murder and discovery | | 02:34 | Sgt. McLean's description of the crime scene | | 03:41 | Evidence gathering—cigarette butts | | 04:20 | Doug Dupe informed, initial police suspicion | | 05:11 | Police clear Doug, rumors abound | | 06:12 | Discovery of murder weapon | | 07:22 | Witness recounts seeing suspect, description for police sketch | | 08:56 | 2001 DNA match: Ernest Gordon Strowbridge | | 09:45 | Plan for an undercover “Mr. Big” sting | | 11:52 | Strowbridge confesses to crime boss (audio) | | 13:32 | Strowbridge confesses again after arrest | | 15:18 | Sentencing, Doug Dupe reflects on justice and closure |

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Takeaways

• Forensic Breakthroughs: Modern DNA analysis can revive 'cold' cases even after a decade.
• Undercover Police Tactics: The “Mr. Big” sting is controversial yet effective in eliciting confessions when direct evidence is lacking.
• Community and Grief: The episode illustrates the ripple effect of violent crime in close-knit communities and the emotional journey for victims’ families seeking closure.
• Justice and Closure: Family members may struggle with sentencing outcomes, even in successful prosecutions.

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Cold Case Files underlines how perseverance, scientific advances, and creative investigation techniques can bring resolution—even decades after a murder.

Transcript

[A]

An A and E original podcast, this.

[B]

Episode contains descriptions of violence. Use your best judgment. Cape Breton is a small island at the tip of Nova Scotia in Canada. While traveling on the road that circles around the island, a person would pass a state park that offers whale watching. They would see forests and coastline, and they would even discover a giant violin statue on the water, a tribute to the traditional fiddle music the island is known for. It's a beautiful place to Visit. But in 1988, Marie and Doug Dupe weren't just visiting Cape Breton. They had plans to retire there. This is Doug.

[A]

We come back to retire and live a slower life, live in the country. We bought a house, six acres of land on the water, and we figured this is going to be it.

[B]

Retiring to a beautiful island seems like it would be a relaxing experience at the very least. And it was. But Marie was becoming bored with her abundance of relaxation time, so she found herself a job at the local convenience store. This is Doug Dup again.

[A]

I asked her, I said, you could find a better job than this. She said, well, I'm going to give it a try. She said, I'm getting bored laying around the house. It's the wintertime, nothing to do. So I'd give it a try. She gave it a try.

[B]

On March 21, 1992, Marie was scheduled for her first night shift at the Big Bend convenience store. That same night, an unscheduled blizzard made an appearance in Cape Breton. Doug pleaded with her to stay home, but Marie was determined to work her shift. Marie had arrived safely at work despite the blizzard. She didn't make it safely back home, though. But it wasn't because the blizzard. That night, while working her shift, Marie was murdered. From AE this is cold case files. Around 4am on March 22, a local man came to the store looking for a cup of coffee to warm him up. Instead, though, he found Marie Dup on the floor surrounded by blood. The man called the police and Sergeant Jim McLean was the one to respond.

[A]

I walked down to the back of the store and I could see that this lady was brutally stabbed. Her throat was slashed, the side of her face was slashed, her right ear was severed right off. She had blood, it seemed to me, coming out of everywhere. I was horrified.

[B]

Marie Dup was still alive, but despite all the efforts to save her life, she died less than an hour after she was found. She had lost too much blood. At the crime scene, the investigators were struggling to find evidence the blizzard had ruined any chance of the killer leaving any type of tracks outside. Inside the Store detective Paul Doyle was also having a difficult time.

[A]

The scene was a mess, of course. The snow was melting and the water was running across the floor and there was blood on the floor and it was even washing in with the exhibits that were on the floor.

[B]

Even though the crime scene had presented many challenges, the investigators had discovered some key evidence. This is Sergeant Dave Morrison.

[A]

There was a lunch counter area in the store. There was one ashtray there that contained one cigarette butt. There was an ashtray on top of the poker machines. I think it had three or four cigarette butts in it. And several cigarette butts were picked up off the floor from various locations in the store.

[B]

In 1992, DNA testing wasn't very widely available in Canada. The cigarettes and cans were collected for future testing. Four hours after Marie had been discovered, the investigators visited the dupe home to both inform Doug of what had happened and likely to also rule him out as a suspect. This is Doug again.

[A]

Three Mallies walking through snow right up to their middle. Finally get to your house. And they walk and they say, well, Doug, we got some bad news for you. Right off the bat I says, my wife did. What else could be the bad news?

[B]

Doug's choice of words was unfortunate because he was then escorted to the police station and investigated as the main suspect. When other people in Cape Benton learned that their newest neighbor was a murder suspect, the investigators were flooded with false tips. Among them were rumors of drug dealing and mafia ties. Here's Detective Doyle.

[A]

I think this was just ended up being a rumor that somehow got started and fed on itself. And as people heard this rumor, their felt it was their obligation to pass it on. And it was based on nothing.

[B]

After several more interviews and two polygraph tests, the police determined that Doug Duke didn't have any involvement in his wife's murder. The investigation had to start again. From the beginning, Homes.com knows that when it comes to home shopping, it's never just about the house or condo. It's about the home. And what makes a home is more than just the house or property. It's the location and neighborhood. If you have kids, it's also schools, nearby, parks and transportation options. That's why homes.com goes above and beyond to bring home shoppers the in depth information they need to find the right home. And when I say in depth, I'm talking deep. Each listing features comprehensive information about the neighborhood, complete with a video guide. They also have details about local schools with test scores, state rankings and student to teacher ratio. They even have an agent directory with the Sales history of each agent. So when it comes to finding a home, not just a house, this is everything you need to know all in1place.homes.com. we've done your homework. In early April, the snow in Cape Breton had started to melt and a new lead was on the verge of being uncovered. Outside the convenience store, the detectives discovered the handle of a knife sticking out of some dirty snow. It was a sandwich knife used at the lunch counter in the store, and the blade was stained with blood. The blood was tested and identified as belonging to Marie Duke. Believing it was likely a store customer that had murdered Marie, the investigators used the receipts to identify who had been at the store the night of the murder.

[A]

We tracked each transaction that took place from the time Mrs. Stoop got to work. We found out who made the purchase and we went and we interviewed that person.

[B]

One of the only purchases that the police couldn't track down happened at 3:16am it was a pack of cigarettes. At 3:18am A different customer, a woman, had bought a sub sandwich. She told the police what she remembered from that night. So we walked into the store and.

[A]

The guy that was just standing over.

[B]

There at the table, he was just like, not moving. It was like a statue. And the only movement that you seen out of him was like when he was having a puff of a cigarette or when he went to lift up his coffee cup. Other than that, he was like a statue. He didn't move. And I had asked the lady, I said, does he bother you? And she said, well, yeah, he's creeping.

[A]

Me a little bit.

[B]

I said, well, maybe you should call the police because, like, he seems a little, you know what I mean, spaced out. And it was just weird looking. The witness helped the police to develop a sketch of the stranger. He was a young looking white man wearing a blue Jays baseball cap. He said, do you think that if you've seen this guy, you would recognize him? I said, yeah. And he said, how do you figure that? I said, the eyes. The eyes would give him away because I've never seen eyes that deep and as I would say, like dead. For the next year, the police actively investigated thousands of leads and interviewed hundreds of suspects. But they didn't come any closer to identifying the man in the sketch. In 1997, seven years after Marie Dup was murdered at the Big Bent convenience store during her night shift, the evidence was able to be tested for DNA. The unknown genetic profile that was developed was entered into the Canadian DNA databanks. It wasn't until the summer of 2001 that a match to the profile was found. Here's Detective Doyle again.

[A]

Ernest Gordon Strowbridge was a young guy from Newfoundland. He came over to the Cape Breton area when he was 17 years old. He worked at a few different locations around Cape Breton.

[B]

At the time of the murder, Strobridge only lived a couple of miles from the convenience store. By 2001, he had moved to Ontario. So Detective Boyle contacted Detective Glenn Bowmaster from the Ontario Provincial Police. He explained that they were looking for Strobridge because of the DNA match. This is Detective Bowmaster.

[A]

Well, really, all the DNA did was put him in the crime scene. It's a pretty big stretch from putting someone in the crime scene to saying he committed the murder.

[B]

Detective Bowmaster thought that Doyle would need a confession to make his case. He suggested that he went about it delicately.

[A]

You have one kick at it here, and I think once you burn that bridge. And he now knows he's a suspect. If he's not confessing, it's too late to try and do something.

[B]

After that, Bowmaster planned an undercover operation to trick his suspect into talking about the crime. On September 8, 2002, Gordy Strobridge had a meeting in the hotel penthouse with a person he believed was a Canadian crime boss. The crime boss was actually Detective Bob Deasy, Bowmaster's colleague.

[A]

The scenario is quite simply the suspect coming forward to a job interview.

[B]

Strobridge had been the subject of an undercover sting running with members of a supposed crime family. He stood lookout while people unloaded bootleg liquor and delivered packages he thought contained stolen diamonds. Now the time had come for Strowbridge to be promoted. Here's some of the audio from the meeting between Detective Deasy and Gordie Strobridge.

[A]

You know why you're up here tonight? I wanted to meet. Maybe it's possible that you can come into our little family, which I'm very much home to. When he realizes that this is the kind of life I would really like to have, and then I'll explain to him exactly the. The insurance policy of the crime family is that you need to offer us something of equal value because we certainly don't want to lose what we have. Once we kind of bare our souls to you, we're exposed and there's got to be a trade off.

[B]

Yeah, the trade off they were referring to was reeling any big crimes that Strobridge had committed. Here's more audio from the meeting.

[A]

I was closer. There was a thing called the big Benz murder. Big Benz? Yeah, Mercedes Benz. No, it was a Convenience store on Princess Street. And I didn't realize I'd done it until, like, the next day because I blacked out. And then when I woke up next day, I was covered from at the toe and black. Okay, you kind of lost me. What are we talking about? Well, there was a murder there. Yeah. And I done it. That's pretty heavy. All I can remember seeing is she was flashing around this knife. She was. Yeah. So I grabbed a knife and I stabbed her. I sliced control, blood everywhere.

[B]

Detective Deasy had to think quickly on his feet.

[A]

That really took me aback. And I then had to think backwards from that point because essentially we began with the climax. I think he was as nervous as I was. I believe that he was viewing this as the break of his life. He was finally going to be secure in a crime family. And I think he was so anxious to start that procedure that he began the interview with confessing to the murder.

[B]

The conversation went on for around an hour, and when it was over, Strobridge felt confident in his decision to share.

[A]

The only reason why I told you is because. Understood. You know, it's part of the trust. Trust relationship part. I appreciate that.

[B]

The day after the meeting, Strowbridge was having a very different kind of conversation in the interrogation room with Detective Doyle.

[A]

God, you kind of had a. I guess a bit of a surprise there this afternoon. Do you remember being at the hotel last night? Yeah. In Toronto. And do you remember talking to a guy by the name of Bob Deasley? Do you remember telling him that you killed a lady at Big Ben's on Prince Street, Sydney? I don't recall. You don't recall telling him that? It's on videotape. I think it was starting to sink in that he was in trouble. And, you know, he was there because he was going to be charged. And what he told me was what he told the undercover operator. It doesn't mean that I don't regret. Doesn't mean that I don't feel bad. It doesn't mean that I'm not human. It doesn't mean that I don't feel bad for the family. It doesn't mean that. Listen, Gordon, I know that you're human, and it's a pretty big burden for a young man if you're so. So I know that.

[B]

Hi, I'm Juliette Cowley, a retired FBI profiler and host of the true crime podcast the Real FBI Profilers. If you're fascinated with true crime and criminal profiling, then join us as we discuss real cases and examine the behavior exhibited before, during and after the commission of the crime. You can listen to the consultation wherever you get your podcasts. It's as close as it gets to being in the room with the FBI's Behavioral Analysis Unit. Almost one year after his videotaped statements, Ernest Gordon Strowbridge pled guilty to murder. Because Strobridge was a juvenile when he killed Marie Dup, he was sentenced juvenile time, a life sentence with a possibility of parole in seven years. Doug Duke doesn't believe that the sentence is enough, but at least he was able to find some peace through closure.

[A]

No, it's not enough. No. He did his first 12 years not being caught. That was his parole. Guy should be doing life right now. But I'm glad it was before I went to my grave myself because it's nice to see it settled.

[B]

Cold Case Files the podcast is hosted by Brooke giddings, produced by McKamey, Lynn and Steve Delameter. Our executive producer is Ted Butler. Our music was created by Blake Maples. This podcast is distributed by Podcast one. The Cold Case Files TV series was produced by Curtis Productions and is hosted by Bill Curtis. You can find me BrookeGinnings on Twitter and Brooke the Podcaster on Instagram. I'm also active in the Facebook group Podcast for Justice. Check out more Cold case [e-mail] or learn more about cases like this one by visiting the A E real crime [e-mail] realcrime.

[A]

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[B]

What the hell?

[A]

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