Attorneys for the son of the former Cooper Health System's CEO want a drug charge dismissed against him, alleging the case is being prosecuted because the family publicly criticized the death investigation of his parents.

In a memorandum filed Tuesday in Somerset County Superior Court, the attorneys for Matthew Sheridan also allege that authorities lacked probable cause to search his Jeep where they found a small amount of cocaine Sept. 28, 2014, the day Cooper CEO John P. Sheridan, 72, and his wife, Joyce, 69, died.

The court filing also alleges Somerset County officials then promised Matthew Sheridan they would not prosecute him as long as he cooperated with authorities for the death investigation.

The attorneys want a Somerset judge to dismiss the possession charge against Matthew Sheridan, 42, who lived with his parents in Montgomery Township.

"The state has retaliated against Matthew Sheridan for his family's public criticism of the Somerset County Prosecutor's Office handling of his parents' death investigation," according the memorandum. "This type of vindictive prosecution is discriminatory and unconstitutional. The court should grant Matthew Sheridan's motion to dismiss the indictment."

John and Joyce Sheridan were found dead in the master suite that had been set on fire.

Geoffrey Soriano, the Somerset County prosecutor at the time, concluded in March 2015 that John Sheridan fatally stabbed his wife, set the fire, and stabbed himself five times. The deaths were ruled murder-suicide.

The family had hired their own forensic pathologist, Michael Baden, to do a second autopsy on John Sheridan. Baden concluded John Sheridan more likely was killed in an attack, partly because authorities never found the weapon that caused his narrow and deep wounds.

Days after the deaths, Somerset County Assistant Prosecutor Robert Hawkes wrote a letter to the Somerset County Superior Court's Criminal Division that said, "At this time, no indictable charges will be authorized" against Matthew Sheridan.

In Tuesday's memorandum, Sheridan's attorneys, Henry Klingeman and Ernesto Cerimele, noted that Matthew Sheridan had been with friends on Fishers' Island in New York when his parents were found. He and his three brothers - Mark, Daniel, and Timothy - all rushed to the house before going to the Montgomery Township Police Department to assist with the investigation.

There, John Sheridan's brother, Peter Sheridan, a federal judge in Newark, met with the sons when they were told by a detective that they were not suspects and agreed to questioning without an attorney present, according to the memorandum.

That afternoon, when a detective applied for a warrant to search Matthew Sheridan's Jeep, a Somerset County Superior Court judge concluded there was probable cause to do so.

The memo argues that the deaths and the fact that Sheridan lived with his parents does not equate to probable cause or "pass constitutional muster."

"If that were the case, the automobiles of any person residing with a crime victim could be searched and scrutinized," the memo said.

On Oct. 3, 2014, Matthew Sheridan and his attorney met with Hawkes and agreed to be interviewed again "only after representations were made concerning the dismissal" of the charges, according to the memo.

The memo also includes an affidavit from Peter Sheridan that says when he attended a Jan. 23, 2015, meeting with the family and investigators, Hawkes told him that his nephew would not be prosecuted.

The memo also alleges that Soriano told Matthew's twin brother, Mark - a lawyer - that Matthew would not be prosecuted, which was not "special treatment," but what would be done for anyone given the circumstances.

In March 2015, six months after the deaths, Soriano released the murder-suicide conclusion. The family immediately responded, telling the media the suicide ruling was a way to close the investigation and cover up incompetence within the prosecutor's office and the state medical examiner's office.

A month later, the Somerset County Prosecutor's Office referred the drug case to the Middlesex County Prosecutor's Office for prosecution to avoid conflict or appearance of conflict between Somerset and the Sheridans. In April 2016, Matthew Sheridan was indicted on a cocaine possession charge.

"In spite of the fact that this type of speech, 'occupies a preferred position in our system of constitutionally protected interests,' the Somerset County Prosecutor's Office, and now the Middlesex County Prosecutor's Office, seek to retaliate against the Sheridans for their exercise of that speech," according to the memo.

Somerset County's current prosecutor, who started in March, declined comment Tuesday. The Middlesex County Prosecutor's Office did not respond to a request seeking comment. Sheridan's drug case is scheduled for a hearing in Somerset County on June 15.

bboyer@phillynews.com

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