The Metropolitan Crime Commission is asking the state Attorney General’s Office to investigate whether St. Charles Parish District Attorney Joel Chaisson II gave preferential treatment to a former Destrehan High School teacher who accepted a plea deal that allowed her to avoid prison or registering as a sex offender, despite admitting that she had sex with a 16-year-old student.

MCC President Rafael Goyeneche said Chaisson improperly changed the terms of the deal after the fact to defendant Shelley Dufresne’s benefit. Goyeneche also said Chaisson should have recused his office, as all three of the judges on the St. Charles Parish bench — including Dufresne’s father, Emile St. Pierre — did.

In a letter sent Wednesday to Louisiana Attorney General Buddy Caldwell, Goyeneche said Chaisson “mishandled” the case, and he called for “an investigation by an impartial, external agency to ascertain if any criminal violations have been committed.”

When she accepted the deal, Dufresne, 32, was facing one felony count of carnal knowledge of a juvenile, which carried a potential sentence of up to a decade in prison and a $5,000 fine. The charge stemmed from a sexual encounter with the teenage boy at a home in Montz.

Under her deal, Dufresne instead was allowed to plead guilty to one misdemeanor count of obscenity and received a deferred sentence of three years in prison, plus three years of active probation and a $1,000 fine. The original felony charge of carnal knowledge is being held open during her probation period.

The deal allows Dufresne to avoid prison as long as she doesn’t contact the victim or his family and completes 90 days of treatment at a mental health facility by the end of August. She also has to forfeit her teacher’s license.

Goyeneche said he sees several issues with how Chaisson handled the case.

He said Chaisson should have joined the judges in recusing his office on the grounds that the DA “routinely prosecutes matters in the court of the defendant’s father.”

The letter also claims the court proceeding did not follow state law because Chaisson’s office made substantive amendments to the second bill of information — the one with the added obscenity charge — the day after she was sentenced.

Court records indicate that on April 10 — the day after Dufresne accepted the plea deal — Chaisson’s assistant prosecutor, Julie Cullen, filed a “corrected/amended” bill of information, which changed the statute cited in the obscenity count.

Under the statute cited in the earlier version, Dufresne would have been required to register as a sex offender. But that was not part of the deal she agreed to, and so a different statute was substituted in an amended — third — bill.

“Even though Ms. Dufresne admitted in open court that she had sex with a student of Destrehan High School where she was a teacher, court records will reflect only that she pled guilty to transmission of an advertisement containing sexually explicit material,” Goyeneche said.

In a statement and a brief interview Thursday, Chaisson defended his actions. He said the obscenity statute is “complicated” and that Dufresne in fact “may have received a harsher sentence than the penalty provisions” of the obscenity law allowed.

He also noted that if Dufresne fails to comply with her sentence or tries to challenge the deal, she has already admitted to the felony carnal knowledge count that’s currently suspended.

In such a scenario, Chaisson said, he would press ahead with prosecuting her on the suspended charge, which carries a harsher sentence.

Chaisson reaffirmed his decision to prosecute the case, pointing out that Cullen herself formerly worked in the state Attorney General’s Office. “By his (Goyeneche’s) reasoning, the Attorney General’s Office couldn’t handle the case, either, because they prosecute a lot of cases in this court, as well,” Chaisson said. “I’ve got a job to do, and I did it by assigning this to Julie Cullen, and I think she’s done a good job.

He noted that Dufresne has already met with probation officers and started her 90-day inpatient mental health treatment program.

Dufresne is due back in parish court Sept. 1 to review her compliance with the terms of her probation, he said. “In order to make certain that she has a legal felony probation, she has agreed through her attorney that on that date they will file any motions and take any necessary steps to correct any legal or technical issues with her felony sentence and will reaffirm all of the conditions imposed in connection with her plea agreement,” he said.

Goyeneche’s letter said that by brokering the deal and being present during the guilty plea, Chaisson created “the appearance that preferential treatment and political considerations took precedence over the law.”

“This represents, in my opinion, a contempt to the public to not acknowledge the truth of what happened in this case,” Goyeneche said in an interview.

“People make mistakes,” he added, “but with this, there’s so many mistakes, so many fundamental mistakes, that it begins to raise the question: Could this DA be wrong this many times, or was this intentional to accommodate the daughter of a sitting judge in his jurisdiction?”

Chaisson has said the victim’s family supported Dufresne’s plea deal.

Dufresne could still face separate charges from an alleged three-way sexual encounter with the same student and a fellow teacher, 24-year-old Rachel Respess. That incident is alleged to have happened at Respess’ apartment in Kenner after a Destrehan High football game in September.

Kenner police booked both women on identical charges of carnal knowledge of a juvenile, indecent behavior with a juvenile and contributing to the delinquency of a juvenile, but they have yet to be formally arraigned on the allegations in Jefferson Parish.

Follow Richard Thompson on Twitter, @rthompsonMSY.