A teenager pleaded guilty to killing one man and wounding another in a series of 2006 Indiana highway sniper shootings, but the deal left relatives of the slain man angry.

Zachariah Blanton, 18, of Gaston, was scheduled to stand trial next week on charges of murder, attempted murder and criminal recklessness. He pleaded guilty Monday in Jackson Circuit Court to lesser charges of voluntary manslaughter with a deadly weapon and criminal recklessness.

Jackson Circuit Judge William Vance accepted the agreement and set sentencing for Dec. 27. Blanton could be sentenced to anywhere from 20 to 50 years in prison. State law recommends a 30-year sentence.

Prosecutors say Blanton fired his hunting rifle into Interstate 65 traffic on July 23, 2006, from an overpass near Seymour, about 60 miles south of Indianapolis.

One of the shots went through a pickup truck's windshield and killed 40-year-old Jerry L. Ross of New Albany. An Iowa man traveling in another pickup truck also was injured.

Police say Blanton later shot at cars along another highway northeast of Indianapolis, but no one was injured. Blanton, who was 17 at the time, was arrested at his home two days later.

The teen said little during his guilty plea as his attorney, Bruce MacTavish, recounted events leading up to the shooting. He said Blanton had spent several days hunting with family members, but he left them after a disagreement erupted over whether he should help clean some deer.

MacTavish said an uncle assaulted Blanton and ripped his shirt, and a great uncle swore at him and told him to never come back.

The teen left feeling "intense passion and sudden heat of anger," MacTavish said. He drove through Seymour and stopped on an I-65 overpass. He loaded his .270-caliber Remington bolt-action rifle and aimed it at a white pickup truck carrying Ross.

"You knew there'd be people in the truck, didn't you?" MacTavish said.

"Yes," Blanton replied.

"And you knew anyone hit with that deer slug would be killed," the attorney said.

"Yes," the teen answered.

Blanton's defense attorney did not publicly comment after court, and The Associated Press left a message at his office.

Several of Ross's relatives wearing "Justice for Jerry" buttons gathered outside the courthouse before the guilty plea to say they were unhappy with the deal.

His father, 70-year-old Jesse Ross, had been with his son at car races in Indianapolis the day of the shooting and they were headed back home to New Albany.

He said a jury should decide Blanton's fate.

"Twelve people would be about as fair as it could be, it couldn't get no better than that," Ross said. "I don't think this is right, the way they're doing it. All we want is a fair trial because you can't bring nothing back."

Jerry's twin brother, Terry Ross, said many family members were going to stay out of the hearing as a protest. Terry Ross was in the truck with his brother when he was shot.

"He committed those crimes, he should be standing trial for them," he said. "He didn't give Jerry any kind of a deal."

Prosecutor Rick Poynter said after the hearing that he understands the family's anger, but he had to make a decision based on the strength of his case. He noted that Vance had ruled that statements Blanton gave police were inadmissible.

If Blanton was tried for murder, he could have faced 45 to 65 years in prison. But Poynter said the jury also could have acquitted him or found him guilty of reckless homicide.

That would have come with a shorter sentence of between two and eight years in prison. That possibility was "a risk that was too great to take," Poynter said, noting that Ross' family is emotional and he didn't blame them.

"I would be emotional, but I think they would be a lot more emotional if the killer of their loved one walked out of jail in four years, and that could happen," he said.

Evidence against Blanton included a rifle seized from his grandparents' home that prosecutors said matched bullet fragments pulled from vehicles shot along I-65 and on I-69 near Muncie.