Richard J. Shenkman, who is serving a 70-year sentence for kidnapping his ex-wife at gunpoint five years ago, holding her hostage for 13 hours and setting fire to his South Windsor home after she escaped, has lost an appeal of his conviction.

The state Appellate Court upheld Shenkman’s conviction in an opinion to be published on Dec. 9.

Shenkman, who is now 65, was sentenced to 70 years in prison in 2012 after a Hartford jury rejected his plea that he was not guilty by reason of insanity when he kidnapped Nancy Tyler. The couple, who had homes in South Windsor and Niantic and had operated a public relations firm together, had been involved in a bitter, drawn-out divorce.

Appellate judges F. Herbert Gruendel, Elliot D. Prescott and Thomas A. Bishop, in a decision authored by Gruendel, rejected claims that trial Judge Julia D. Dewey improperly denied information to the defense and misled the jury during her instructions prior to their deliberations. The court also rejected a claim that Shenkman was a victim of legal double jeopardy.

Senior Assistant Public Defender Adele V. Patterson, who brought the appeal on Shenkman’s behalf, declined to comment. It is unclear whether she will appeal to the state Supreme Court.

Senior Assistant State’s Attorney Mitchell S. Brody, who defended the appeal, said the case was “won and lost at the trial level, and in connection with the insanity defense.”

The jury found Shenkman guilty of first-degree kidnapping, violation of a protective order, carrying a pistol without a permit, two counts of second-degree threatening, first-degree threatening, third-degree assault, interfering with a police officer, attempted assault of a police officer and first-degree arson.

Shenkman claimed Dewey improperly denied the request of his attorney, Hugh F. Keefe, for a detailed statement of the charges called a “bill of particulars,” which impaired his ability to prepare a “double jeopardy” defense. The appellate decision notes that prosecutor Vicki Melchiorre had laid out the case in detail in an “oral proffer” during a court pretrial court hearing.

The court wrote that Shenkman “has not demonstrated, as he must, that he was prejudiced by the court’s denial of his motion for a bill of particulars.”

The appeals court also rejected Shenkman’s claims he was subjected to double jeopardy by being charged with both interfering with police and attempted assault on a police officer.

In her oral proffer, Melchiorre had explained that the interfering charge stemmed from Shenkman’s refusal to release Tyler from the house and his refusal to surrender his gun after exiting the burning house. The attempted assault charge, the prosecutor said, stemmed from Shenkman’s firing of shots toward SWAT officers posted outside the house.

Similarly, the court ruled that the two threatening charges arose from different incidents. The first charge involved Shenkman’s physical threats to Tyler as he ordered her into the basement, and the second involved repeated threats he made during negotiations with police that he would kill Tyler and blow up the house, according to the decision.

Finally, the appellate judges rejected Shenkman’s argument that Dewey, in her instructions to the jury, misled the panel to believe that if they found him not guilty by reason of insanity, he would be released from confinement prematurely. The appeals court determined Dewey’s instruction properly conveyed that Shenkman would not be released until he was no longer determined to be a threat to society.

“The appellate issues were straightforward and not central to the trial, except for the jury instruction claim, which instruction the court said was proper,” said Brody.

Shenkman, who is expected to die in prison due to his age and the length of his sentence, is being held at the Cheshire Correctional Institution, according to the Department of Correction.

k.florin@theday.com

Twitter: @KFLORIN