20/20 Podcast – “What The Killer Left Behind”

Podcast by ABC News | January 31, 2026

Overview: Main Theme & Purpose

This episode of 20/20 examines the harrowing true crime case of Amanda Plass, a beloved 20-year-old woman brutally murdered in her Chicopee, Massachusetts apartment in 2011. Through in-depth interviews and the voices of Amanda’s family, friends, investigators, and even the accused, the episode explores the winding, tension-filled investigation—the major false leads, a unique clue hiding in plain sight, and the determined quest for justice led by Amanda’s relentless mother. The case ultimately pivots on the forensic evidence Amanda "left behind," and the tenacity of all those who refused to abandon her memory.

Key Discussion Points & Insights

The Discovery & Aftermath of Amanda Plass’s Murder

• Initial Shock and Scene Description

  • Amanda fails to show up for her waitressing shift at Friendly’s, alarming family and coworkers ([04:08]).
  • Seth Green, Amanda’s boyfriend of just one week, discovers her body—stabbed multiple times, throat slit—on her kitchen floor; he is inconsolable and frantic ([04:37], [05:56]).
  • Scene is described as “brutal,” indicative of a heated, violent struggle ([06:21]; [06:39]).

• Family Devastation

  • Amanda’s mother, Michelle Penna, and sister, Amy Lee, recount the agony and disbelief upon learning of the murder ([07:31], [08:12]).
  • Michelle’s struggle with not only grief but also with practicalities—funeral arrangements, expenses, the search for answers ([08:39], [09:07]).

Early Investigation: Suspects & Dead Ends

• Everyone Is a Suspect

  • “Every single person in her life was a suspect. Everybody.” – Amy Lee ([01:33], [09:55])
  • Police immediately focus on Seth Green due to the nature of the crime and his proximity, especially after he admits a work knife is missing ([10:01]–[10:39], [16:24]).

• Seth Green’s Ordeal

  • Seth describes being interrogated and suspected, even though he called 911 and was distraught ([16:52], [24:03]).
  • Ultimately, Seth’s timeline, DNA, and shoe size do not match the evidence ([23:24]).

• Other Leads: Ex-Boyfriend Jesse, Friend Mercedes Benz

  • Amanda’s recent ex, Jesse, is scrutinized due to jealousy and suspicious text message deletions. However, alibi and shoe evidence clear him ([25:55]–[31:18]).
  • Friend/colleague Mercedes Benz is observed at the scene but is cleared through surveillance footage ([33:25]–[35:40]).

Forensic Evidence & Lingering Mystery

• Physical Clues

  • “The most important piece of evidence found at the crime scene: a bloody sneaker print.” – Narrator ([21:17])
  • Palm print on a broken window and blood under Amanda’s fingernails (DNA).

• Stalled Case & Desperate Measures

  • With no clear suspects or DNA matches, the case stagnates. Michelle campaigns tirelessly, putting up a billboard, holding memorials, balloon releases, and keeping Amanda’s case in the public eye ([38:00], [38:14]).
  • The investigation is further shaken by a scandal: two police officers take and share unauthorized crime scene photos, prompting a lawsuit and lasting trauma for Amanda’s family ([44:55]–[46:25]).

Breakthrough: A Name in Plain Sight

• Hidden Clue on a Whiteboard
  • More than two years later, police review photos and spot “Dennis was waz here” written on a whiteboard in Amanda’s bedroom—a name no one in Amanda’s orbit recognizes ([47:45]–[48:47]).
  • Cell phone records connect Amanda to Dennis Rosa Roman, previously unknown to police except for a prior unrelated arrest.

The Confrontation & Interrogation of Dennis Rosa Roman

• Dennis’s Story Unravels

  • Initially, Dennis denies knowing Amanda or visiting her apartment but is cornered as the evidence (phone records, DNA, shoe size, palm print) mounts ([53:53]–[57:43]).
  • At first, claims he only sold Amanda marijuana, then admits to being in her apartment, later insists he merely witnessed the crime and tried to save Amanda, shifting his story with each new fact pressed by police ([64:05]–[66:41]).

• DNA Confirms the Killer

  • “The DNA that was found under her fingernails connects you to her. You know what? It doesn't just get there.” – Detective Ronald Gibbons ([65:58])
  • Dennis’s Air Max shoe also matches the bloody print at the scene.

• Motive Remains Unclear

  • Dennis never admits guilt—final story is that he intervened in a struggle started by another man, but never supplies a name or evidence for this claim ([66:16], [72:19]).
  • Police theorize a possible motive: Dennis intended to steal marijuana from Amanda’s apartment, and Amanda became a victim of circumstance ([76:51]).

Trial & Aftermath

• Prosecution’s Case

  • Prosecutors bring together converging forensic evidence and Dennis’s changing stories ([71:04]–[71:54]).
  • Defense tries unsuccessfully to argue Dennis was a bystander to another’s violence.

• Verdict & Sentencing

  • Jury finds Dennis Rosa Roman guilty of first-degree murder after five hours’ deliberation ([75:13]–[75:20]).
  • Michelle and family speak of profound relief, but also the persistent ache—true justice feels elusive since Amanda is gone ([75:46], [78:14]).

• Legacy and Reforms

  • Michelle’s lawsuit leads to a $110,000 settlement for the crime scene photo scandal; she also lobbies for and helps pass “Amanda’s Law,” banning unauthorized photos by first responders ([78:47]).
  • Michelle dedicates herself to victim advocacy and keeping Amanda’s story alive ([79:14]).

• Ongoing Legal Uncertainty

  • Due to changes in Massachusetts law regarding juvenile sentencing, Dennis (convicted at age 20) could be eligible for parole as early as 2028—Amanda’s family vows to contest this ([80:41]–[80:55]).

Notable Quotes & Memorable Moments (with Timestamps)

• On the Pain of Loss

  • “Not knowing how to even comprehend what had happened, but then still knowing that, okay, I need to put my child to rest.”
    — Michelle Penna (Amanda’s mother), [01:17], [08:39]

• Community Suspicion

  • “Every single person in her life was a suspect. Everybody.”
    — Amy Lee (Amanda’s sister), [01:33]

• The Turning Point—‘Dennis was here’

  • “On the whiteboard, there was wording in it. Dennis was waz here.”
    — Detective Ronald Gibbons, [41:16], [47:57]

• The Breakthrough

  • “The DNA that was found under her fingernails connects you to her.”
    — Detective Ronald Gibbons, [65:58]

• Justice, Yet Incomplete

  • “Justice will never be served because she’s dead and he’s not.”
    — Michelle Penna (Amanda’s mother), [78:14]

• Strength & Advocacy

  • “Do you feel like she’s with you now?” — Narrator
    — “Oh, absolutely. All the time.”
    — Michelle Penna, [80:19]

• Amanda’s Motto & Legacy

  • “Keep your face to the sun. Never look back at your shadows. Just like her precious sunflowers.”
    — Michelle Penna, [80:27]

Key Segment Timestamps

| Timestamp | Segment Description | |------------|------------------------------------------------------------------------| | 04:37 | Seth Green’s 911 call, discovery of Amanda’s body | | 10:01 | Police begin to suspect Amanda’s boyfriend, Seth | | 21:17 | Bloody sneaker print evidence discovered | | 23:24 | Seth cleared as a suspect | | 31:18 | Jesse (ex-boyfriend) cleared | | 39:05 | Hoax confession, case stalls | | 44:55 | Police officers’ crime scene photos scandal surfaces | | 47:45 | Whiteboard clue "Dennis was here" discovered | | 53:53 | Detective Gibbons confronts Dennis Rosa Roman | | 65:58 | DNA matches Dennis to scene | | 75:13–20 | Jury returns guilty verdict | | 78:47 | “Amanda’s Law” passed | | 80:27 | Michelle Penna’s message about Amanda’s enduring legacy |

Conclusion

“What the Killer Left Behind” weaves a devastating portrait of loss and dogged perseverance. The episode stands as a testament to familial love, the power of forensic evidence, and the real-world consequences of persistence in the fight for justice. While Amanda’s murderer has been brought to justice, her family continues to grapple with lingering questions and the impact of her loss—ensuring that Amanda’s light continues to shine, and her story warns and inspires others.