The “Suicide Pact” in the Garage Was a Lie: A Doctor’s Affair, a Hose, and Two Bodies That Didn’t Belong Together

The photo is filed as police evidence from a quiet residential street in Portland, Maine. At first glance it looks like the kind of scene investigators see too often—tragic, simple, already explained.

A silver sedan sits inside a garage. The engine is running. The windows are fogged from the inside, as if the car itself is sweating. A hose snakes from the exhaust pipe up to a rear window, sealed tight with tape.

Inside the car are two bodies: a man and a woman.

Both dead from carbon monoxide poisoning.

In 2003, police ruled it a double suicide—a pact between two people who chose to end their lives together. The case was wrapped up quickly, the narrative tied with a bow of grief and logic: stress, betrayal, hopelessness.

But if you look closer—at the positioning of the bodies, at the angle of the hose, at details investigators didn’t understand or didn’t question—something starts to feel wrong. The kind of wrong that doesn’t scream; it whispers. The kind of wrong that waits for time and technology to catch up.

Because what that photo really captured wasn’t a suicide at all.

It was a double murder, staged so convincingly that it took almost a decade for anyone to realize the truth.

And when the truth finally came out, it didn’t just expose a killer. It exposed a respected professional who hid evil behind a clean smile—then went on hurting others for years, convinced he was untouchable.

Two Perfect Families on the Same Street

In Portland in the early 2000s, the neighborhood had its “perfect” couples. The kind people envy and imitate—nice homes, good jobs, children in good schools, church on Sundays, polite waves in the driveway.

Two families fit that picture: the Richardsons and the Marshalls.

They lived close. Their kids crossed paths in the same schools. Their lives overlapped through the same church and Bible study groups. They had occasional dinners. From the outside, they looked like the American dream in duplicate.

Behind closed doors, both marriages were cracking.

And those cracks would become an entry point for something deadly.

The Dentist Everyone Trusted

In 2001, Dr. David Richardson was 35 years old—a dentist with a thriving practice in downtown Portland. He was charming, successful, and deeply woven into the church community. People trusted him instinctively, the way communities trust men who look stable and respectable.

He and his wife, Catherine Richardson, had been married for 12 years and had four children.

Catherine was 32, a homemaker who poured herself into raising the kids and serving the church. Friends described her as sweet and deeply religious—someone who baked for fundraisers, organized community events, and believed marriage was sacred. Trust came naturally to her. Suspicion didn’t.

Just blocks away lived the Marshalls.

Brian Marshall was 38, a Portland police officer who had served the community for more than 15 years. He was respected in his department. His wife, Grace Marshall, was 30, a part-time teacher with her own strong ties to the church.

Two families, one community, one set of values—at least in public.

Then, in early 2002, something shifted.

The Affair That Started Quietly—and Then Consumed Everything

It began the way affairs often begin: plausibly, quietly, with a story people can tell themselves to make it feel harmless.

Extra conversations after church.

Coffee.

Text messages that started friendly and turned flirtatious.

Then secrecy.

Then lies.

David Richardson and Grace Marshall crossed a line, then kept walking until the line vanished behind them.

For David, the affair felt like escape. His marriage to Catherine had become routine and predictable. Catherine’s world revolved around children and church. David wanted something else—travel, excitement, a sense of being desired. Grace made him feel young again.

For Grace, the affair filled a void Brian didn’t even know he was creating. Brian worked long hours, came home tired and stressed, emotionally unavailable in ways Grace felt but couldn’t name. David was attentive. Romantic. Present. He made her feel chosen.

They convinced themselves it wasn’t just lust—it was love. And like most people caught in that self-deception, they began to fantasize about a life where the obstacles simply… disappeared.

By the summer of 2003, the affair was in full swing. They met multiple times a week. They exchanged hundreds of texts and emails. They talked about running away together.

But reality stood in their way.

And those obstacles had names.

Divorce Would Cost Too Much—So They Chose Something Worse

Catherine, David believed, would never agree to divorce. She was deeply religious and saw marriage as sacred. Even if David tried to leave, she would fight it—and she’d likely get the kids, the house, and a major portion of what David had built: his reputation, his practice, his standing in Portland.

Divorce threatened David financially and professionally.

Brian Marshall was a different kind of barrier: a police officer with training and a gun. If Brian discovered the affair, David and Grace feared what could happen. Grace, in particular, was terrified of confronting him.

So the fantasy darkened.

What if Catherine and Brian weren’t part of the equation anymore?

At first, it was hypothetical—venting, drama, words said in secret that feel unreal because they’re whispered.

Then it became a plan.

Then it became an obsession.

David, with medical knowledge and access to drugs, began researching ways to kill that could look accidental. Grace started keeping track of Brian’s routines—when he was asleep, when he was vulnerable, when no one would notice.

By September 2003, they chose a method they believed was perfect:

Carbon monoxide poisoning staged as a double suicide.

They constructed a story in advance. Both victims could plausibly be “under stress.” Brian from his demanding job. Catherine from a husband pulling away. If they were found dead together in a car, it could look like they had discovered the affair and made a suicide pact.

The community would mourn.

No one would suspect.

David and Grace would be “free”—a grieving widower and widow who found comfort in shared tragedy.

The plan was set for September 19th, 2003.

The Night They Drugged Their Spouses

On the evening of September 18th, David made his first move.

He gave Catherine a drink laced with sleeping pills, telling her it would help her relax. Catherine had been having trouble sleeping because of tension in the marriage. She trusted her husband completely.

She drank it without question.

When Catherine was unconscious, David called Grace. Grace drove to the Richardson house—leaving Brian asleep at home. Together, they loaded Catherine into David’s car and drove her to a secluded location: an abandoned garage on the outskirts of Portland.

Then Grace went home.

And she did the same thing to Brian.

She gave him sleeping pills in his evening tea. When he was out, she called David. David came to help move Brian to the same garage where Catherine was waiting—still unconscious.

By 4:00 a.m. on September 19th, both Catherine and Brian were inside David’s car in that garage, sedated and defenseless.

Then David attached a hose from the exhaust pipe to the rear window, sealing it with duct tape, and started the engine.

David and Grace waited outside the garage—holding hands—while carbon monoxide filled the car.

It took roughly 45 minutes.

Neither Catherine nor Brian ever woke up.

When they were certain both were dead, they staged the scene. They positioned the bodies so it would appear the victims had been sitting together. They planted a vague typed note about being overwhelmed by life’s pressures. They locked the doors in a way David had researched—using a coat hanger through a cracked window to trigger the lock.

Then they went home separately.

And waited for someone else to discover the bodies.

The “Suicide Pact” That the Whole City Believed

Around 10:00 a.m. on September 19th, a maintenance worker at an industrial park noticed a car in the garage with its engine still running. When he looked inside and saw two people slumped over, he called 911.

Police and paramedics arrived quickly, but it was too late. The car was filled with toxic fumes. The victims were already dead.

The scene looked exactly like what it had been designed to look like:

A double suicide by carbon monoxide poisoning.

When police identified the bodies as Catherine Richardson and Brian Marshall, Portland reeled. These weren’t strangers. Catherine was a beloved church volunteer. Brian was a decorated police officer.

Why would they die like this?

Why together?

Detectives began investigating—and almost immediately found the affair between David Richardson and Grace Marshall. Friends said they’d noticed David and Grace growing close. Messages revealed Catherine had confronted David about Grace days before her death. Brian had reportedly suspected Grace was cheating.

The narrative wrote itself:

Two betrayed spouses discovered the affair, felt humiliated and hopeless, and ended their lives together.

Tragic.

But it made sense.

The typed note seemed to confirm it.

David and Grace played their roles perfectly. David broke down at Catherine’s funeral in front of the congregation. Grace was grief-stricken at Brian’s memorial service, supported by officers who felt terrible for their colleague’s widow.

The police investigation wrapped up within a month. The medical examiner confirmed carbon monoxide poisoning. The doors were locked from the inside. The note didn’t raise enough flags.

Case closed.

David and Grace had gotten away with murder.

The Marriage Built on Murder

About six months later—after what looked like a “respectable” mourning period—David and Grace began seeing each other openly. They told friends they found comfort in one another through shared grief. Some people felt uneasy about how fast it happened, but the community largely accepted it.

They were both single now.

Why shouldn’t they be happy?

David and Grace married in 2005, combining families—David’s four children and Grace’s two—into a blended household that looked, from the outside, like proof that healing was possible.

Inside, it was rot painted to look like stability.

David began having nightmares—waking up seeing Catherine’s face, hearing her voice. He couldn’t confess without destroying himself. He couldn’t go to therapy without risking exposure. He was trapped with his secret.

Grace became paranoid. She saw suspicion in every sideways glance, every whisper. She started drinking heavily to quiet the anxiety.

Their marriage—built on lies and bodies—turned toxic. They fought constantly. David became controlling and emotionally abusive. Grace became bitter and resentful. The kids suffered in the middle.

And still, they stayed.

They had to.

If one talked, both went down.

Years passed. David’s dental practice thrived. He opened a second location. His reputation in Portland grew.

But the man behind that professional façade was collapsing.

He started drinking. Taking pills to sleep. Pills to wake. Pills to get through the day.

And then he crossed another line—one that revealed how completely he believed he was beyond consequence.

The Predator in the Dentist’s Chair

Around 2008, David began sedating female patients more heavily than necessary during dental procedures. At first he told himself it was for comfort.

Then he started touching them while they were unconscious.

Small violations that escalated.

More patients.

More assaults.

David had already decided morality was negotiable. He had murdered two people and walked free. In his mind, that made him untouchable.

Then, in early 2012, one patient woke up mid-procedure—groggy, but aware enough to understand David’s hands were where they shouldn’t be.

She confronted him afterward and threatened to report him.

David panicked. He begged. Offered money. Offered free dental work for life—anything to keep her silent.

She left traumatized and unsure what to do.

That night, David broke.

The guilt. The fear. The accumulated lies. The knowledge that he had killed two innocent people and then violated others afterward.

He couldn’t carry it anymore.

“I Killed Them Both.”

On March 15th, 2012, David Richardson walked into the Portland Police Department and asked to speak to a detective about the 2003 deaths of Catherine Richardson and Brian Marshall.

Detectives assumed he had new information. A memory. A clue.

Instead, David said five words that detonated a case the city thought was buried:

“I killed them both.”

For the next six hours, David gave a detailed confession: the affair, the plan, the sleeping pills, the garage, the hose, the staged scene. He provided details only the killer would know.

Then he confessed to the sexual assaults—names, dates, what he’d done.

It was a full unburdening.

When asked why now, David broke down in tears. He said the guilt was destroying him. He wanted to face justice.

Police took him into custody immediately and began verifying the confession.

Everything checked out.

But one question remained:

What about Grace Marshall?

David’s confession implicated her as an equal participant.

Detectives brought Grace in for questioning. She denied everything, insisting David was having a breakdown and trying to take her down out of spite. Their marriage, she said, had ended badly; they divorced in 2010. This was revenge.

Investigators weren’t buying it.

Phone records from 2003 showed hundreds of calls and texts between David and Grace in the weeks before the murders. Emails showed them discussing being together “no matter what it takes.”

And then came the turning point—the evidence photo from the original scene.

The Detail in the Photo That Police Missed for Years

Forensic experts re-examined the old crime scene photos in 2012 and noticed what had been missed in 2003.

The way the hose was attached to the exhaust required someone to be outside the car. The angle was wrong for someone inside to have done it. The duct tape sealing the connection had fingerprints—partial prints too degraded to identify with the technology available in 2003.

But in 2012, enhancement techniques were better.

Those prints matched Grace Marshall.

She had been there.

She had helped build the “suicide” scene.

Confronted with the fingerprint match, Grace changed her story. She admitted she was present—but claimed David forced her, that she was terrified, that he threatened to kill her if she didn’t cooperate.

Investigators didn’t believe her. The messages and planning suggested she wasn’t coerced—she was committed. Witnesses came forward saying Grace had talked about wanting to be free of Brian.

Grace Marshall was arrested and charged with two counts of first-degree murder.

A case closed for nine years exploded into the biggest story in Maine: a respected dentist and his mistress murdered their spouses, staged it as suicide, then lived freely for nearly a decade.

Trials, Verdicts, and the Weight of Betrayal

The trials were held separately.

David’s trial came first in late 2012. Prosecutors laid out the affair, the plan, the confession, and the forensic reanalysis that proved staging. David’s defense focused on leniency—his confession, his mental state, the idea that he “finally did the right thing.”

The jury wasn’t sympathetic.

They found David Richardson guilty of two counts of first-degree murder and multiple counts of sexual assault.

Grace’s trial followed in early 2013. She maintained coercion, but prosecutors presented emails and texts showing her active involvement, evidence she drugged Brian, and proof she benefited from the murders and lived with David afterward.

After five days of deliberation, the jury found Grace guilty of two counts of first-degree murder.

The convictions brought closure—but also reopened pain. Catherine’s family had spent nine years believing she took her own life, wondering if they missed warning signs. Learning she’d been drugged and killed by the husband she trusted shattered them all over again.

Brian’s fellow officers were devastated. They’d mourned him as a suicide victim, not a murdered colleague. And the widow they comforted—Grace—had been part of it.

The children from both families faced an unbearable reality: one parent murdered, the other involved.

At sentencing, the judge called the crimes among the most cold-blooded and calculated he had encountered. He noted that David and Grace continued to victimize others for years—Grace by accepting sympathy as a grieving widow, David by assaulting patients under anesthesia.

David Richardson received two consecutive life sentences with a minimum of 25 years before parole eligibility, plus additional time for assaults. Grace Marshall received two consecutive life sentences with a minimum of 22 years before parole eligibility.

Catherine Richardson was 32. A devoted mother who believed in people’s goodness.

Brian Marshall was 38. A police officer who spent his career protecting others—never realizing the greatest threat to his life slept in his own home.

Their deaths were staged as suicide. Their names were tainted by a lie for nearly a decade.

But the truth surfaced anyway—carried, ironically, by the man who once thought he’d buried it forever.

And it started with a single photo: a running engine in a closed garage, fogged windows, a hose taped into place—evidence of a “suicide pact” that was never real.