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“What the Killer Left Behind”: 20/20 Reports on Amanda Plasse Homicide January 30 2026

Ryan Gill

Airing Friday, January 30, 2026, ABC’s 20/20 episode “What the Killer Left Behind” takes viewers inside one of Massachusetts’ most haunting cold cases—the 2011 murder of Amanda Plasse. The special report, led by Ryan Smith, explores the brutal slaying of a young waitress in her Chicopee apartment and the relentless pursuit of justice by her mother, Michelle Plasse, whose determination never wavered through years of frustration and heartbreak.

 

The Crime That Shattered a Community

On August 26, 2011, Amanda Plasse, a 20-year-old waitress beloved by many in Chicopee, Massachusetts, was found stabbed to death in the kitchen of her third-floor apartment. She was discovered by a new boyfriend who had grown concerned after she missed work. The crime scene showed clear signs of a violent attack. Amanda had been stabbed multiple times and her throat was slashed. Bloody shoeprints and a palm print on a window added further evidence, but no signs of forced entry pointed investigators toward someone she might have known.

The attack was described as brutal and personal. Investigators initially focused on those close to Amanda, including the man who found her. But after polygraphs, shoe size comparisons, and DNA analysis, those leads fell away. The killer’s identity remained elusive, and frustration grew as months passed with no arrest.

A Mother’s Refusal to Let the Case Go Cold

Amanda’s mother, Michelle Plasse (later Penna), took on the responsibility of keeping the investigation alive. She organized public events, distributed flyers, and remained a constant voice demanding justice. Her persistence pushed detectives to revisit the case, and in late 2012, they began reviewing every detail again, from the forensic evidence to photographs of Amanda’s apartment.

That renewed investigation uncovered a crucial clue that had been previously overlooked. On a dry erase board in Amanda’s bedroom was a chilling inscription: “Dennis was here 8/11/11.” Investigators had missed this earlier, but now it opened a path they hadn’t pursued before.

The Name That Led to a Breakthrough

Detectives didn’t recognize the name “Dennis” from previous interviews. It had never come up with Amanda’s known acquaintances. Investigators cross-referenced her phone records and social media history, eventually identifying a man named Dennis Rosa-Roman who lived just blocks away.

When detectives interviewed Rosa-Roman, he initially denied ever having been in Amanda’s apartment. But after being shown the photograph of the whiteboard, he admitted to writing the message. That contradiction raised alarms. Rosa-Roman then gave conflicting accounts about his interactions with Amanda, eventually claiming he tried to help her but was too afraid to come forward. Investigators didn’t believe his shifting stories.

DNA collected from Amanda’s fingernails matched Rosa-Roman. His shoe size—7.5—also matched the bloody footprints found at the scene. With that evidence, authorities arrested Rosa-Roman in November 2013, two years and two months after Amanda’s murder.

The Trial and Conviction

Rosa-Roman was charged with first-degree murder and pleaded not guilty. During the trial, prosecutors argued that Amanda had likely confronted him about prior break-ins at her apartment and that the murder was premeditated. The jury heard how Rosa-Roman left physical evidence behind, including his DNA and even his name on her bedroom whiteboard.

After an eight-day trial and five hours of deliberation, the jury returned a guilty verdict in July 2016. Rosa-Roman was sentenced to life in prison without the possibility of parole. For Amanda’s family, the conviction brought a sense of closure—but not peace. Michelle Penna described the long wait and the agony of uncertainty as unbearable.

A New Legal Twist Reopens Old Wounds

In 2024, the Massachusetts Supreme Judicial Court ruled that mandatory life without parole sentences for individuals aged 18 to 20 were unconstitutional, citing neuroscience suggesting diminished impulse control in emerging adults. As a result, Rosa-Roman, who was 20 at the time of the murder, became eligible for a parole hearing.

Amanda’s family was blindsided. In October 2025, they received a letter informing them that Rosa-Roman would be eligible for parole in 2028. Outraged, Michelle Penna and Amanda’s sister, Aimee Lee Reyes, spoke publicly about the emotional toll of reopening a wound they had only just begun to heal from.

They joined other families across Massachusetts in questioning how such a decision could be made without regard for victims’ rights. The Hampden County District Attorney’s office vowed to oppose parole for Rosa-Roman at every opportunity, arguing that the brutality of his crime should disqualify him from any future release.

The Legacy of Amanda Plasse

Amanda Plasse was known for her creativity, kindness, and energy. A lover of art and self-expression, she left an impression on everyone who knew her. Her murder devastated her family, friends, and community, but her mother’s refusal to give up ensured that her case was not forgotten.

The 20/20 episode “What the Killer Left Behind” highlights how one clue hidden in plain sight—a name scribbled on a whiteboard—finally unlocked the truth. But it also underscores the lingering impact of violent crime on surviving families, particularly as legal rulings reshape what justice means years after a conviction.

Amanda’s story continues to resonate, not just for the tragedy of her loss, but for the power of a mother’s fight to bring the truth to light. Through tireless advocacy, community support, and unwavering resolve, Michelle Penna helped achieve the justice her daughter deserved—only to find herself, once again, at the frontlines of a legal battle.

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