NEW BRUNSWICK--Declaring that Michelle Lodzinski will be "old and gray" when she is released, a Middlesex County judge Thursday sentenced the former New Jersey woman -- convicted last year in the murder of her young son whose mysterious disappearance and death remained unsolved for more than two decades -- to 30 years in state prison with no possibility of parole.

Prosecutors, who had reopened its long-dormant investigation into the death of 5-year-old Timothy Wiltsey after a review of its cold-case files, had sought life imprisonment.

"She coldly and callously murdered her child and threw his body in a ditch. She left him to decompose so that a cause of death was never determined," said Middlesex County Deputy First Assistant Prosecutor Christie Bevacqua. "A mother who kills her child should spend the rest of her life in prison. The rest of her life."

Her attorneys said they expected to file an appeal within a week.

Timothy Wiltsey, who was 5-years-old and in kindergarten when he vanished, and Michelle Lodzinski at the time of her son's disappearance in 1991. (Star-Ledger file photo and AP file photo)

Lodzinski, a former South Amboy resident, was convicted last May of first-degree murder in the death of Timmy, who she claimed had disappeared one evening from a traveling carnival in Sayreville in 1991. His skeletal remains would be discovered 11 months later in a marshy area near the Raritan Center in Edison, where the then-23-year-old single mother worked.There was never any forensic evidence linking her to the boy's death, nor a determination as to how he died.

Lodzinski did not testify during her trial.

On Thursday, there was silence in the second floor courtroom of Superior Court Judge Dennis Nieves as Lodzinski, 49, wearing a green sweatshirt and denim pants, was brought in to finally hear her sentence.

In a dramatic hearing lasting more than an hour, both the prosecution and defense made impassioned arguments over how long Lodzinski should remain in prison. Under state statute, the options were limited.

Her attorney, Gerald Krovatin, argued that the judge should impose a 30-year sentence, the least possible time under the state statute for first-degree murder.

"That sentence is sufficient. It's more than sufficient," he said. "I'm sure Timmy would not want to impose a life sentence on his mother."

His remarks drew an immediate objection from prosecutors.

She said Lodzinski got away with the murder of her son for 25 years before her arrest and deserved no mercy.

"She stands convicted of murdering her own child and getting away with it for 25 years. She made sure she was able to lead the life she wanted to live because she no longer had the burden of her first-born child," Bevacqua said."She was able to lead the life she wanted to live because she got rid of her biggest burden."

Bevacqua, who presented her arguments while a slideshow of photos of Timmy ran continuously on a screen in the courtroom, told the judge the only fair sentence was life in prison.

Lodzinski declined to address the court.

"I'm sure she'll be criticized for that," Krovatin said. But he said one "cannot accept responsibility for a crime that you deny to this day that you committed."

However, he read letters written in support of Lodzinski from family members, friends in Florida where she was living with her two teenage sons who were born after Timmy, as well as fellow prisoners at the county jail, where she has been incarcerated since her 2014 arrest.

One inmate who had befriended Lodzinski in prison said she was considered a "den mother" by her fellow prisoners.

"All of them...describe Miss Lodzinski as one of the kindest, gentlest persons they knew," Krovatin said.

Throughout the hearing, Lodzinski showed little emotion. Her long dark hair covered most of her face, which she occasionally dabbed with a tissue.

Nieves asked Lodzinski to stand and look at him "eye to eye" as he prepared to impose her sentence. He asked her several times if she wanted to address the court, but she repeatedly declined with a shake of her head.

"He was a good looking kid," the judge told her. But he said the photo from the trial that still stays in his head is the one of the boy's skull in a ditch where the remains were found. "I'll never forget it," the judge said.

The judge said he had kept much incriminating evidence away from the jury that would have been prejudicial to her case. But in the end, he said, it came down to her, and the many falsehoods she repeatedly told investigators.

"The reason you were found guilty, Michelle Lodzinski, is because the jury believed that you lied, you lied, you lied again. You lied, you lied and you lied," he told her.

But Nieves said he did not believe Lodzinski deserved a life sentence, imposing a term of 30 years with no parole. She received credit for 884 days she has already spent in prison, which will reduce her 30-year sentence by more than two years.

After the hearing, Middlesex County Prosecutor Andrew Carey expressed satisfaction that the long case had concluded with Lodzinski in prison. He said he often hears from police officers and people on the street who still remembered the case like it was yesterday.

"The wheels of justice sometimes move a lot slower than we would like in this business, however, in this case, justice was served," Carey said.

Joe Mulvanerton, 55, of Old Bridge, an alternate juror in the trial who did not sit in on deliberations, attended the sentencing. He said he was hoping Lodzinski was sentenced to life in prison, but he's "satisfied she won't see the light of day for 30 years."

"She was supposed to be his protector and she killed him," Mulvanerton told a throng of reporters in the courthouse lobby.

He said he was surprised Judge Nieves sentenced Lodzinksi to the least possible time under the guidelines, but he respected the process.

"I think she was given every opportunity for a fair trial," Mulvanerton said.

Lodzinski has always denied she had anything to do with her son's death.

The reported disappearance of the kindergartener in May 1991 captured national headlines. The young single mother told police she had left Timmy for a moment to buy a soda and when she turned around, he was gone. However, a search of the carnival grounds turned up nothing and police could find nobody who could even recall seeing the boy there that evening.

While suspicions quickly centered on Lodzinski, whose often emotionless and at times bizarre behavior raised immediate questions, there never was any direct evidence or eyewitnesses linking her to her son's death. It would be more than 20 years before authorities finally decided to charge her.

Investigators later revealed they had zeroed in on Lodzinski from the start. They expressed frustration that she changed stories about what happened the day he disappeared, and inconsistent answers to their questions, revealing later that her account of Timmy's disappearance repeatedly changed in the days and months after she first reported him missing.

At first she said he wandered away. They said she claimed a woman named "Ellen," a former go-go dancer she knew casually, offered to watch Timmy while she went to the concession stand. Later, she told detectives that Ellen and an unidentified man kidnapped the boy at knifepoint.

Equally troubling was their observation that she showed little emotion over the disappearance of Timothy.

"Everyone is waiting to see a grieving mother on TV break down, crying, hysterical because the public they thrive on that stuff. But I'm not going to do it," she told reporters as the search went on.

Fliers with photos of Timothy Wiltsey that were posted after the 5-year-old reportedly disappeared. (Star-Ledger file photo)

Photos of the cute little boy adorned thousands of milk cartons and the case was featured on the television show "America's Most Wanted." But in the end, Timothy's remains were discovered nearly a year later, in a creek at the Raritan Center industrial park.

A cause of death was never established because of the deterioration of the few bones that were found. With no forensic evidence, traces of DNA or eyewitnesses, no charges were filed and the case remained in limbo for decades. When the Middlesex County Prosecutor's office began re-examining a number of its unsolved murders, however, they took another look at a faded blue-and-white child's blanket discovered near the creek where Timothy was found.

The frayed fabric became a smoking gun to dectectives. They said the blanket had originally been shown to Lodzinski and her mother early in the investigation, but both claimed not to recognize it. Prosecutors acknowledged that the FBI and State Police found no forensic evidence linking it to Timothy, his mother, or their home. But they said Lodzinski's niece, who often would baby-sit the boy, had a visceral reaction when she saw it, "bursting into tears."

In August 2014, again a single mother with two teenage sons born in the wake of Timothy's death, Lodzinski was arrested near her Florida home in Port St. Lucie--on the day her son would have turned 29--and charged in his death.

The blanket, introduced in the courtroom, became a centerpiece of the prosecution case.

Middlesex County Assistant Prosecutor Christie Bevacqua holds up the blue-and-white blanket at the center of the case against Michelle Lodzinski. (Patti Sapone | NJ Advance Media for NJ.com)

In her summations to the jury, Bevacqua returned to the blanket: "He was taken out of the world by the very person who brought him into it--his mother," she said. "Then she did something only a mother would do--she left her child with a blanket. Only this blanket did not cover Timmy's remains--it uncovered his murderer."

Krovatin, her defense attorney, argued the case against Lodzinski had been entirely circumstantial, citing not only the failure to determine a cause of death, but the lack of any history of abuse, any evidence linking the blanket to Timmy's home, and no eyewitnesses. He said the entire case hinged on the emotional impact of the death of a 5-year-old boy.

After eight weeks of testimony from 68 witnesses, including retired police officers who had been involved in the case, as well as former neighbors and boyfriends, she was convicted by a jury of seven men and five women.

Staff writers Alex Napoliello and Kelly Heyboer contributed to this report.

Ted Sherman may be reached at tsherman@njadvancemedia.com. Follow him on Twitter @TedShermanSL. Facebook: @TedSherman.reporter. Find NJ.com on Facebook.