AUGUSTA — A convicted killer committed to Riverview Psychiatric Center, who pleaded guilty to escaping from the facility in 2018, had his conviction overturned this week by the state’s top court upon his appeal, ruling he had improperly been tried for the same criminal incident twice.

Mark Ian Gessner

The Maine Supreme Judicial Court ruled Tuesday that Mark Ian Gessner’s escape conviction be vacated and that the charge should be dismissed.

Gessner, 57, was convicted of the 1994 murder of Melvin Henderson, a florist in Bath, for which he was sentenced to 30 years in prison. While serving his sentence for that crime in prison, Gessner was accused of aggravated assault and trafficking in prison contraband. He was found not criminally responsible for those charges and committed to the custody of the Commissioner of Health and Human Services in 2011.

In 2018, while Gessner was living at Riverview, he was on a two-hour pass allowing him to be unsupervised out in the community — purportedly to ride his bike in the Augusta/Hallowell area — and was accused by police of going to the Bath home of his father and threatening him with a knife.

He was arrested and charged with two counts of criminal threatening with a dangerous weapon. However one of those charges was dropped and he was acquitted, at trial in Sagadahoc County, on the other charge.

State officials later filed an escape charge against him in Kennebec County, for which he was indicted, for not returning to the Riverview campus in a timely manner in the 2018 incident.

He pleaded guilty to that charge in August 2020 and was sentenced to 209 days imprisonment, time he already served. But it was a conditional guilty plea that Justice Michaela Murphy noted at the time preserved Gessner’s right to appeal the case to the Maine Supreme Judicial Court.

His attorney Clifford Strike did appeal, arguing Gessner shouldn’t have been prosecuted on the escape charge filed in Kennebec County because the alleged crime arose from the same criminal episode as the Sagadahoc County case. In that case, he had been acquitted of criminal threatening with a dangerous weapon.

The Supreme Judicial Court issued an opinion Tuesday agreeing with Strike and vacated Gessner’s guilty plea. The court directed the dismissal of the indictment in which Gessner was charged with escape.

In the court’s opinion, justices noted the alleged threats against his family members were part of the ongoing “escape” of Gessner and were thus arising from the same criminal incident.

“Although Gessner committed the crime of escape when he crossed the imaginary line marking the boundary of his confinement, his escape was still ongoing when he was apprehended just a short time later in an adjoining county,” the justices concluded, in an opinion authored by Associate Justice Catherine Connors.

State law bans “separate trials for multiple offenses based on the same conduct or arising from the same criminal episode.”

Prosecutors from the Kennebec County District Attorney’s Office had argued that the charge of escape could only be filed in Kennebec County because that is where the crime occurred and where the institution he escaped from is located.

State law does note that prosecution for escape must be in the county in which the institution is located, but also states that “notwithstanding other provisions of this section, in all cases of escape, prosecution may be in the county or division in which the person who has escaped was apprehended.”

The supreme court stated that means the charge of escape could have been brought in Sagadahoc County when Gessner’s criminal threatening case went before a jury, which acquitted him. But it could not be brought up in a second prosecution.

Gessner completed his murder sentence in 2016 after getting credit for “good time,” allowing him to be released after serving some 22 years. But because he had been committed to state custody for the charges made against him in prison, rather than being released when he left prison in 2016, he instead was committed as a forensic patient to Riverview Psychiatric Center.

A forensic patient is someone who’s been involved with the criminal justice system or committed a crime, but was found not responsible for their actions because of insanity.

The Maine Supreme Judicial Court in 2017 upheld a lower court’s ruling that Gessner should not be released into the community.

At Riverview, Gessner at least twice petitioned the courts to be allowed to leave the state mental health facility with patient privileges in order to take part in community activities. A 2016 request was denied, but in 2018 he was granted up to two hours a day of unsupervised time as long as it was within 10 miles of Augusta.

In January 2020, he petitioned the courts to release him from state custody and allow him to leave Riverview, but that request was denied.