A Somerset County investigator has challenged the probe into the September 2014 deaths of Camden hospital executive John Sheridan and his wife.

Jeffrey Scozzafava, a detective with the Somerset County Prosecutor’s Office, contends crime-scene evidence from the couple’s home “was improperly collected, improperly preserved and subsequently destroyed.” The criticisms are part of a whistleblower lawsuit that contends Scozzafava faced retaliation after expressing concerns over the Sheridan investigation and other cases.

The prosecutor’s office has said it believes Sheridan, the 72-year-old president and CEO of Cooper Health System, fatally stabbed his 69-year-old wife, Joyce, in a bizarre predawn attack in the couple’s bedroom. Investigators assert Sheridan then started a fire and took his own life.

FULL COVERAGE: SHERIDAN CASE

The Sheridans’ bodies were found by emergency personnel responding to a blaze at their Skillman house.

The couple’s four adult sons contend the investigation was botched and their father committed no crime. They want John Sheridan’s manner of death to be changed to undetermined.

Among other criticisms, the sons contend investigators failed to look for potential clues outside the couple’s bedroom. They also note investigators never recovered the weapon that killed John Sheridan.

In his lawsuit, Scozzafava contends evidence from the bedroom was left exposed for months, that blood collection swabs were “improperly packaged” and that evidence envelopes were “shoddily taped,” according to the report.

The suit contends Scozzafava was transferred from the Forensics Unit to the Fugitive Unit in retaliation for “lodging complaints regarding deficient and improper evidence collection and casework by the Forensics unit (and his supervisor).”

It also asserts Scozzafava was given a car without a siren or flashing lights, describing that as a “vehicle demotion.”

The suit was filed April 20 in Superior Court, Somerset County.

In February, a group of influential supporters called for a new investigation into the deaths of the Sheridans, who had been married for 47 years. The group, Friends of John & Joyce Sheridan, include three former New Jersey governors and Cooper Chairman George E. Norcross III.

One day later, the office of Gov. Chris Christie announced Geoffrey Soriano, then the Somerset County prosecutor, would leave office in early March.

John Sheridan was an influential Republican, serving as transportation commissioner for former Gov. Thomas Kean and chairman of NJ Transit Corp. from 1982 to 1985. He was a deputy attorney general and assistant counsel for Gov. William T. Cahill.

More than 200 people attended a November 2014 service for the couple at the Trenton War Memorial, where speakers included Gov. Chris Christie.