Douglas Herlihy case: How investigators cracked cold case of father Paul Herlihy’s beating death in New Hampshire

More than two decades after Paul Herlihy was beaten to death, court documents show how investigators say they were able to gather enough evidence to charge his son in the killing.

Investigators say they talked to a number of the father and son’s friends and family members about the months leading up to the 50-year-old’s 2003 killing,  an arrest affidavit that prosecutors shared with News says.

They ultimately set up a call between Douglas Herlihy, who was 17 at the time of the incident, and his brother, which prosecutors say revealed inconsistencies in his story just one month before his arrest, according to court records.

Christopher Knowles, chief of the New Hampshire Attorney General’s Cold Case Unit, detailed Douglas Herlihy’s statement in court, according to WMUR. The deadly incident happened after the two had engaged in a physical tussle, the affiliate reported.

“He said that he then grabbed a baseball bat the family kept behind the front door and struck his father with it, causing his death,” Knowles said, according to WMUR.

A friend of Douglas Herlihy who spoke to investigators said that during the summer of 2003, Douglas Herlihy complained that his father often hit him, according to the affidavit.

Douglas Herlihy, 40, pleaded guilty to manslaughter and attempted falsification of physical evidence on Wednesday in his father’s death, according to New Hampshire Attorney General John Formella.

The guilty pleas were entered as part of a plea agreement that is subject to the court’s acceptance, according to the attorney general’s office.

As part of the agreement, Herlihy faces a sentence of 12 to 24 years in New Hampshire State Prison on the manslaughter charge, the attorney general said.

The agreement will also include a three and a half- to seven-year sentence, on the attempted falsification of physical evidence charge, which will be suspended for a period of 20 years, the attorney general noted.

Remaining counts Herlihy was indicted on, including second-degree murder, will be dismissed as part of the agreement, according to the attorney general’s office.

“The New Hampshire Cold Case Unit and our law enforcement partners remain committed to pursuing answers and accountability, even decades after a crime. That work takes persistence, patience and a determination to follow the evidence wherever it leads. I commend the investigators and prosecutors whose continued efforts brought this case to an important resolution,” Formella said in a statement.

The attorney general noted that the case “is a reminder that the pursuit of justice does not end with the passage of time.”

A sentencing hearing for Herlihy will be scheduled for early 2027, the office said.

Months leading up to Paul Herlihy’s death

At the time of the killing, Paul and Douglas Herlihy were the sole occupants of a residence in Milford that Paul Herlihy bought in December 2002, according to court documents.

Douglas Herlihy had a “tumultuous relationship” with several family members, including physical confrontations and violence with his father, according to an arrest affidavit that prosecutors shared with News.

In the months leading up to his death, Paul Herlihy called police at least eight times due to Douglas Herlihy’s behavior including to get his son removed from the home, according to the affidavit.

Paul Herlihy also transferred his son to a school for students with behavioral disorders, but Douglas Herlihy tried to avoid attending while there, according to the affidavit.

On Aug. 12, 2003, Douglas Herlihy was found in Paul Herlihy’s vehicle, which had been reported stolen, and local police found drugs and other illegal items in the car, the affidavit said. Herlihy was charged with several offenses, according to the affidavit.

Douglas Herlihy was arraigned and released on bail posted by his father, the affidavit said.

On Aug. 18, 2003, Paul Herlihy brought his son to the Milford Police Department to self-surrender for the stealing of the car, the affidavit said. Doug Herlihy pled guilty to that charge in Milford District Court andthe  court imposed a 90-day suspended sentence and a $500 suspended fine, according to the affidavit.

Before his death, Paul Herlihy left a message on his ex-wife’s answering machine on Aug. 23 telling her he was going to have Douglas Herlihy’s bail revoked but did not explain why, according to the affidavit.

Paul Herlihy’s last known contact was a call later that day to his nephew, according to the affidavit, which said he left an emotional message saying “Doug was gone again.”

Paul Herlihy was killed in his Milford residence between Aug. 23, 2003, and Aug. 27, 2003, the attorney general’s office noted.

He was found in his home on Aug. 27, 2003, during a welfare check carried out by Milford Police, according to the affidavit.

Responding officers found hundreds of flies and a strong odor of decomposition in the residence when they arrived, according to the affidavit. In the kitchen, it says they found a rug that was pulled up and rolled and a blue tarp covering the carpet. When they removed the tarp, they discovered what was later determined to be the body of Paul Herlihy within the carpet, according to the affidavit.

An autopsy determined the death was a homicide as a result of blunt force trauma, the affidavit said. It noted that the chief medical examiner found that Paul Herlihy also had a broken nose, a jaw fracture and basal skull fractures.

The arrest

Investigators orchestrated a phone call between Douglas Herlihy and his brother Andrew Herlihy in May 2025 in which Douglas Herlihy claimed he sat down for interviews with investigators and said they determined it would have been impossible for him to have anything to do with his father’s death, according to the affidavit.

But, investigators said that there is no evidence Douglas Herlihy participated in an interview with the cold case investigators looking into his father’s death, the affidavit said.

Douglas Herlihy also told his brother that police broke down the time of death to within an hour or two and, based on cameras on Route One, determined it would have been impossible for him to have anything to do with his father’s death, according to the affidavit.

Investigators say they found nothing to indicate police either located or were directed toward any surveillance video that would exclude Douglas Herlihy as a suspect in his father’s death, according to the affidavit.

Douglas Herlihy was arrested and charged in the death of his father in June 2025, according to the attorney general’s office, which said he was initially charged with second-degree murder in his father’s death.