MANCHESTER — Trial began Tuesday for an 18-year-old whose comments about bringing a gun to his high school graduation.

John Thomas, 18, faces decades in prison on charges of solicitation to commit murder, solicitation to commit first-degree assault and two counts of criminal threatening last June. He has been in jail since the incident, unable to afford $10,000 cash-only bail.

At issue is a comment made to a friend prior to Hillsboro-Deering High School’s graduation: “Am I the only one bringing a loaded handgun to graduation?”

After the jury was seated Tuesday in Hillsborough County Superior Court, prosecutor Donald Topham didn’t find anything funny about it.

“I don’t see anyone laughing,” Topham, an assistant Hillsborough County attorney, told the jury. “You’re not laughing because that’s not funny. That’s not a joke.”

Why would anyone make such a comment unless he wanted to shoot, kill or terrorize people? Topham asked jurors.

The trial started two days before the first-year anniversary of the killing of 17 students and staff at the Marjory Stoneman Douglas High School in Parkland, Fla., by a former student. The shooting heightened concerns nationwide about kids, guns and the vulnerability of schools.

Thomas was arrested three hours before graduation and has been held at Valley Street jail since then, according to his mother, Darlene Wellner. The solicitation to commit murder charge carries a penalty of up to 30 years in prison.

“Yes, my son made an inappropriate joke, an inappropriate comment,” Wellner told the New Hampshire Union Leader. “Does he deserve to be in jail for the last eight months? No. Does he deserve to be tried for solicitation to commit murder? No.”

Thomas is being represented by public defender Suzanne Ketteridge. In her opening remarks, Ketteridge said the charges reflect a rumor mill run amok and an overreaction by police and prosecutors.

Ketteridge told the jury the prosecution won’t be presenting testimony that Thomas owned guns, nor that he had access to guns nor that he planned to acquire guns. Nor will jurors hear about plans, text messages or tweets alluding to such plans, she said.

“John wasn’t planning to do anything that day except graduate,” Ketteridge said.

According to testimony, Thomas made the comments to a friend, William Corey, during a morning graduation practice at Hillsboro-Deering High School. Graduation was scheduled for that evening.

The first two witnesses for the prosecution were former classmates, Zachary Rowell and Kiyle Brown Leberon, who said they overheard the conversation.

Rowell and Leberon spoke in whispers and short sentences, preferring generalities to specifics. For example, Rowell said: “I heard him and another student talking about bringing a gun and if they had a gun or something.”

And Brown testified that Thomas and Corey spoke about shooting up the graduation, that Thomas would bring an assault rifle and Corey a shotgun. But in a police report, Leberon only mentioned bringing guns and nothing about “shooting up” the graduation.

The third student, Dylan Conover, spoke more distinctly and used the words in the indictment — that Thomas had asked if he was going to be the only one to bring a loaded handgun to graduation.

Conover said it made him nervous and uncomfortable, so he spoke to Hillsboro-Deering principal James O’Rourke.

Ketteridge described her client as an average kid who had friends, played football and video games, and was on the robotics team. He started a movie club as a freshman at Hillsboro-Deering High School that he ran for all four years, she said.

Thomas’ mother said that club was a haven for autistic students who weren’t welcome in other clubs. After graduation, Thomas had a scholarship to pursue mortuary science in Massachusetts and an internship lined up with a Manchester funeral home. Those plans were all been put on hold after his arrest, Wellner said.

With both she and her husband living on disability, they lacked the resources to post bail. Wellner said her son has had challenges to overcome — ADHD, depression and anxiety — but is determined to make something of his life.

The family moved from Everett, Mass., to Hillsborough when Thomas was in seventh grade to escape violence in Massachusetts. But New Hampshire held new threats, according to the mother.

“They’ve bullied him since the seventh grade,” Wellner said of his classmates turned accusers. “Now, he’s sitting in court fighting for his life.”

Wellner said the family has no guns at home, but she’d talked with him in the past about school shootings.

Thomas liked playing with paintball and Airsoft guns, she said. He and friends cleaned up the backyard of a disabled veteran in town and he let them use his land to target practice, she said.

According to Wellner, prosecutors offered Thomas a plea bargain of 10 years in prison, which he refused.

Prosecutors dropped charges against Corey in July, and he is scheduled to testify on behalf of Thomas.

Testimony in the trial is expected to conclude Thursday.