WHEN a respected lawyer was found dead in a burning bedroom alongside his wife of 47 years, the authorities ruled it was a murder-suicide.

John and Joyce Sheridan were both discovered lying face up with multiple stab wounds to their bodies, with two kitchen knives, matches and a gas can lying nearby.

Joyce had first- and second-degree burns and 12 wounds, mostly to her head and hands. John, chief executive at a New Jersey hospital, was lying under a fallen wardrobe and showed signs of smoke inhalation, indicating that he had been alive after his wife died.

The 72-year-old had five knife wounds to his neck and torso and a blunt-force injury that had caused five broken ribs.

Just days after the deaths on September 28, 2014, the prosecutor’s office was hinting that they had identified the culprit, expressing confidence there was no threat to the community.

Detectives told the Sheridans’ four sons it was clear that their father had killed their mother, set fire to the room and taken his own life.

But the sons are convinced someone else was involved, telling the New York Times their father had no motive or mental health problems and that other explanations have not been explored. Police found no evidence of infidelity, financial strain, serious illness or arguments that might explain why the former state transportation commissioner would kill his wife.

The prominent family took matters into their own hands, hiring a pathologist called Michael Baden to help find the truth. The holes quickly started to emerge.

Mr Baden and the state’s medical examiner determined that one of the two knives, a kitchen carving knife, had been used on Mrs Sheridan. But both doctors agreed that a third, missing weapon had caused Mr Sheridan’s wounds.

When the Sheridan sons were allowed back in the house, they made two strange discoveries, overlooked by investigators.

One was a lump of melted metal, which could have come from a piece of furniture or could have been a weapon, although the melting point for kitchen knives is typically well above the temperature the room would have reached.

The second piece of evidence was a fire poker found in the adjoining bathroom a month later, even though there was no fireplace upstairs. It could have been the cause of the blunt blow to Mr Sheridan’s body.

Six months after the Sheridans died, the prosecutor’s office released a report. It said Mr Sheridan’s wounds were “consistent with self-infliction” and that DNA samples taken from the knives could not exclude him as a suspect, although lab reports were inconclusive, only pointing to a probable white male suspect.

The only suggested motive was that Mr Sheridan was “unusually worried” over a work report into fatality rates after cardiac operations at his hospital. It said family members and colleagues had said he was “disproportionately concerned”, although the New York Times could not locate the people who said this.

Instead, most people portrayed Mr Sheridan as a man of unimpeachable repute, who was incredibly unlikely to commit such a heinous crime, particularly in such a bizarre manner.

“Anyone who knew John and Joyce doesn’t think it’s conceivable,” said Mrs Sheridan’s brother Peter Mitchko. “Nothing makes sense.”

The couple’s son Mark, who followed in his father’s footsteps to become a top Republican lawyer, said he understands people are inclined to dismiss the concerns of his privileged, politically connected family. But he says it doesn’t change that fact that other feasible explanations — that an intruder broke in and killed the couple, for example — have been overlooked.

“I’m sitting at the police station on the day my parents died, and the governor is calling to offer condolences,” he told the New York Times. “Not many people get those calls, right? And at the same time, you’re just getting screwed over, and there’s nothing you can do about it.’’