NIAGARA COUNTY, N.Y. (WIVB) — The Mandy Steingasser murder haunted North Tonawanda for almost 30 years.

On September 19, 1993, 17-year-old Mandy Steingasser went missing and was later found dead in Bond Lake Park in Lewiston.

On January 14, Joseph Belstadt was sentenced to 25 years to life in prison for strangling the teenager.

Growing up in Niagara County at the time of the murder was now-Niagara County District Attorney Brian Seaman.

“I went to high school at Lockport High School, which is a similar-sized school to North Tonawanda High School. I actually graduated from high school the same year Mandy would’ve graduated from high school,” Seaman said.

His first memory of hearing about the case was when he was an assistant district attorney in Niagara County.

“I remember the case being one that there was always an assistant DA assigned to that file, there was always somebody working on it and in North Tonawanda it was the same thing, there was always a detective assigned to the case and working on the case. So it was something that- anytime a young person is killed people don’t forget that and this case was not forgotten.”

Over the years, police and the DA’s office never stopped looking for new technologies and forensic methods to test evidence.

In 2018, two pubic hairs found in the backseat of Belstadt’s car were tested in a new way.

They matched Steingasser’s DNA and Belstadt was arrested.

The trial started in Lockport in 2020, but ended quickly in a mistrial because of the pandemic.

Seaman had been asked to look over the case in the past as an assistant district attorney but it wasn’t until that mistrial, during his run for district attorney, that he really got involved.

“That was kind of the moment that I realized, because I had already announced as a candidate for district attorney at that time and I was looking forward and seeing this trial is gonna be one of the things I was going to have to address and handle in my first year.”

His two assistant district attorneys, Mary Jean Bowman and John Granchelli, had been working the file for four years and were familiar with the details.

The case was re-assigned to Judge Michael Mohun from Wyoming County and jury selection began.

“You don’t want a juror who knows a lot about the case either from the press or from talking to other people you want a juror who is able to just hear what happens in court and not have any outside information they’re relying on. So we were very careful about that during jury selection making sure that if anyone had information about the case, it was of a type they could put aside.”

The trial started on October 25, 2021, exactly 28 years after Steingasser’s body was found in Bond Lake Park.

“In this case there was no eyewitness to the crime but there was a lot, a lot of different pieces of evidence that when you put it all together it told a very compelling story. It painted a very compelling picture about what happened that night, but you had to be very careful and you had to pay close attention to all of those details.”

Seaman and his team laid out those details throughout the trial including one in particular that sticks out to him.

“Mandy was found at this particular place in Bond Lake and it was a very out of the way place, it wasn’t unknown as it no one else had ever been there, but it was out of the way. You had to know about the place to get there, there was no signage for it there wasn’t picnic tables, it wasn’t an area that was well-demarcated. Yet the defendant had taken a girl to that place just a couple weeks before.”

Another important detail was the timeline of the night Steingasser went missing.

“It’s another kind of amazing thing is that we had certain time markers in this case from 28 years ago that were set in absolute stone. We had punch cards from the police department the exact time a certain call had come in, the exact time a certain police officer had been dispatched or arrived on the scene.”

Documents were just part of this case, even more compelling were the witness testimonies of the people who were with Steingasser before she got into Belstadt’s car.

“It was very different than any other trial I’ve ever done you were bringing people back in their mid to late 40’s who were talking about something that had happened one night during high school and to see these who were young kids now as grown adults who have families and children who are older than they were at that time coming back and sitting down and testifying it was a very unique experience. As far as memories some witnesses had a very vivid memory of what happened that night to some of these witnesses that’s a night they will never forget in the rest of their life that was the last time they ever saw their close friend or family member.”

The crucial evidence in the case was presented on the eighth day of the trial, the DNA match of those pubic hairs that led Belstadt’s arrest.

The jury listened to days of testimony about these hairs, the defense arguing their presence didn’t mean anything except the fact that Steingasser was in his car that night.

“The evidence in the case was that Mandy got into the defendant’s car and if his account of what happened is to be given any type of belief, she was only in the front seat of that car for a matter of a couple of minutes. And the idea that her pubic hairs somehow then ended up in his backseat then also on the driver’s side floormat that really stretches believability,” Seaman said. “I think the jury saw through any type of argument in that regard and saw, ‘no, this is more consistent with the other evidence, the evidence that there had been a violent struggle.'”

While Seaman said he doesn’t believe the defense was able to cast any real doubt on the important issues of the case, there was one distraction that kept coming up.

“There was DNA found in her underwear but it was conclusively determined to be that of a person that she had had a previous romantic relationship with,” he said. “It was a distraction and it was determined that he was not even in the area on the night that that happened, he had left and he had moved to Florida.”

The trial lasted three weeks and the jury reached a guilty verdict in just a day and a half.

On a chilly January 14 afternoon, Seaman and his team headed to the Niagara Falls courthouse for Belstadt’s sentencing.

Before being sentenced, Belstadt addressed the courtroom, maintaining his innocence.

“I am truly sorry for the pain suffering you all have gone through over all these years but I am not the person who killed Mandy. I am innocent,” Belstadt said that day.

“In a situation like that where a defendant is proclaiming innocence I let the evidence speak for itself. And the evidence in the case it was compelling. It was compelling evidence that he is guilty of the crime that the committed and that’s why we have a trial,” Seaman said.

Judge Mohun gave Belstadt 25 years to life in prison, the maximum sentence.

Belstadt’s attorney Michelle Bergevin vowed that day she wouldn’t stop fighting for justice.

“It’s not going to end here. I will not forget and I pledge to make this wrong right in the future. There will be justice but it’s not today,” Bergevin said.

Seaman said a notice of appeal has been filed, something he said happens in 100% of trials.

“I can’t think of a glaring issue that would lead to a worry about there being a successful appeal but we’ll see what the defense counsel raises,” he said.

For Seaman, this case hit close to home, literally. He saw what the tragedy did to Niagara County and he said if there’s anything he could tell Mandy now…

“Mandy, we did everything that we could here to try to bring some level of justice for you and your family and I’d say that the detectives in North Tonawanda, the individuals that worked the Niagara County Forensic Lab, they never forgot about you.”

Mandy Steingasser is gone, but her impact will live on in the Niagara County community.

Seaman said this is a testament to persistence.

“You can never really heal the wound for them, you can never bring back the loved one, but to be able to do something to be able to work for and achieve some level of justice here in this world it’s an important thing it’s something we need to continue to strive to do not just for Mandy, but for all the victims of crime,” he said.

“It is a case about never forgetting about a victim and never allowing it to just kind of fade away.”

Kayla Green is a reporter who has been part of the News 4 team since 2021. See more of her work here.