Shivangi Sinha
In August 2011, Amanda Plasse was discovered fatally stabbed inside her apartment in Chicopee, Massachusetts. The case initially went cold, with investigators unable to identify a suspect for an extended period. Months later, persistent pressure from Plasse’s family prompted police to re-examine the evidence. During that review, officers noticed a name written on a whiteboard inside the apartment, a detail that had previously been overlooked. That clue led them to Dennis Rosa-Roman, who lived near the scene of the crime. ABC’s ‘20/20: What the Killer Left Behind,’ chronicles the investigation and the sequence of discoveries that ultimately resulted in Dennis’ arrest.
Dennis Rosa-Roman’s Name in Amanda Plasse’s Apartment Redirected the Investigation
Dennis Rosa-Roman lived in Massachusetts and had a criminal history that included breaking and entering. He was also known locally as a marijuana dealer in the Chicopee area and was familiar with Amanda Plasse. He alleged that he had sold marijuana to her in the past. On August 11, 2011, he entered Plasse’s third-floor apartment at 73 School Street in Chicopee without her consent. While inside, he wrote the message “Dennis was here 8/11/11” on a dry-erase whiteboard using a red marker before leaving the apartment. When Plasse’s remains were discovered inside the residence on the evening of August 26, 2011, investigators initially had no identified suspects.
Investigators initially overlooked the whiteboard and instead concentrated on other potential suspects, including Plasse’s former boyfriend and people close to her. Forensic evidence was collected early on, including DNA found beneath her fingernails. Police also documented a palm print on a window that had been broken from inside the apartment, along with a shoe print measuring approximately seven and a half inches in size. Despite these findings, the case stalled. It was not until late 2012, when officers took note of the message bearing the name “Dennis” on the whiteboard, that the focus shifted. This discovery prompted investigators to search for individuals with that name in the surrounding area.
The DNA Found at the Crime Scene Solidified the Case Against Dennis Rosa-Roman
They ultimately identified Dennis Rosa-Roman and found that his phone number matched entries in Amanda Plasse’s call records. In October 2013, police approached Dennis at his home in Westfield, Massachusetts. During that initial contact, he admitted that he had sold marijuana to Amanda Plasse in the past but insisted that he had never been inside her apartment. While speaking with him, investigators discreetly recovered a cigarette he had discarded, which was later used for DNA testing. Dennis also agreed to come in voluntarily for questioning. During his first interview, he consented to an oral swab and disclosed his shoe size, which matched the footprint documented at the crime scene.
He later returned for a second interview. When detectives confronted him with the message written inside Plasse’s apartment, his version of events began to shift. He later changed his account, admitting that he had been inside the apartment and that he was the one who had written the message on the whiteboard. Dennis then claimed that on the night Plasse was killed, he went to her apartment and encountered an unknown man there. According to his revised story, he said he tried to intervene and stop the attack but was unable to save her. He refused to identify this alleged individual because he feared for his own safety and that of his family. Over time, he offered multiple, conflicting versions of what had happened. When the DNA found under the fingernails was found to be a match with Dennis, there was little doubt. In March 2014, he was formally indicted on charges of first-degree murder.
Dennis Rosa-Roman is Being Held in a Massachusetts Prison Today
Dennis Rosa-Roman’s trial got underway in July 2016, and it ended with a jury finding him guilty of first-degree murder. He was sentenced to life in prison without the possibility of parole. In the years that followed, Rosa-Roman pursued multiple appeals, arguing that his Miranda rights had been violated and that there were flaws in the jury selection process. Those challenges were ultimately rejected when the Massachusetts Supreme Judicial Court upheld his conviction in 2020.
A significant legal shift came later, when the same court ruled in October 2025 that mandatory life sentences without parole for so-called “emerging adults” were unconstitutional. Because Rosa-Roman was 20 years old at the time of the offense, the decision made him eligible for parole consideration beginning in 2028. He is currently incarcerated in a Massachusetts state prison, though additional details about his placement have not been made public.
