A Prairieville man suspected of killing his newborn son by placing him in his freezer in Lake Charles 14 years ago has been sentenced to 45 years in prison on unrelated charges in Ascension Parish after he pleaded guilty to having sex with a young teenager, prosecutors said.

Benjamin G. Tonguis, 38, had been set for trial Wednesday on sexual assault charges in the 23rd Judicial District Court in Gonzales but pleaded guilty to four counts of aggravated crimes against nature, court records say.

That plea puts the focus back on the older allegations against Tonguis. Lake Charles Police Department Deputy Chief Mark Kraus said Friday that he and other police investigators, officials in the Calcasieu Parish district attorney’s and coroner’s offices met Thursday after they learned of the plea in Ascension a day earlier.

Kraus, who was one of the original investigators on the 2001 death of the infant, said he hopes the case will be brought back before a Calcasieu grand jury for a possible first-degree murder charge. He said whether that will happen has not yet been determined.

The Calcasieu Parish District Attorney’s Office declined comment on the case earlier this week.

“The case here in Calcasieu is still unresolved and under investigation. We cannot comment any further on the matter,” Holly Carter Holland, a spokeswoman for District Attorney John DeRosier, said in an email.

Tonguis was accused in August 2001 of killing his 9-day-old son, Tristan Tonguis. Kraus said the parish coroner determined at the time that the child was placed in the freezer alive and died of hypothermia. Tonguis was charged with first-degree murder at the time, Kraus said, but the case never went to trial and the charges eventually were dropped against Tonguis.

Holland refused to verify specifics about the old case against Tonguis.

But the American Press reported in March that Amy Tonguis, Benjamin Tonguis’ then-wife, was arrested with him and also charged with first-degree murder. She pleaded guilty in September 2002 to accessory after the fact to murder.

Kraus said when he learned of Benjamin Tonguis’ arrest earlier this year, he and his former partner on the case drove to Ascension to interview him but didn’t have much success.

In the Ascension case, Tonguis, 41149 La. 42, Prairieville, also had faced two more counts of aggravated rape, a charge that brings a mandatory life sentence with conviction. The assaults of the young victim occurred in 2014 and 2015.

But 23rd Judicial District Assistant District Attorney Robin O’Bannon said prosecutors in Ascension agreed not to pursue the rape counts in exchange for the plea.

The plea agreement does not contain language requiring Tonguis to cooperate with prosecutors but does not eliminate the possibility of his prosecution on other charges.

O’Bannon said the plea agreement in Ascension “has nothing to do with the charges in Lake Charles.” She said that case is “still open and still subject to prosecution there.”

Judge Thomas Kliebert Jr., of the 23rd Judicial District, handed down the sentence Wednesday at the Ascension Parish Courthouse Annex in Gonzales. He gave Tonguis prison time without the benefit of probation, parole or suspension of sentence. Tonguis also must register as a lifetime sex offender, prosecutors said.

Tonguis’ defense attorney, Don Williams, could not be reached by deadline Friday.

The 23rd JDC encompasses Ascension, Assumption and St. James parishes.

Follow David J. Mitchell on Twitter, @NewsieDave.