How did 17-month-old Nicholas Miller die in June 2009?

On Monday, jury selection begins in Hastings on the first day of what's expected to be a monthlong trial for the toddler's stepfather, whom a grand jury indicted on suspicion of first-degree murder and other crimes in the death.

The state alleges that Tylar Hokanson, 24, intentionally caused fatal injuries to the toddler in rural southern Dakota County. Assistant County Attorney Cheri Townsend aims to prove that Nicholas then went for days with a broken back and a brain injury, his lungs filling with fluid before he died in Wisconsin's Pierce County at the home of Hokanson's mother.

A team of public defenders, however, plans to call its own expert to testify that Nicholas died of natural causes. Or perhaps, the attorneys contend, the death was an accident.

And if someone did kill the child, the defense attorneys maintain, there could have been other perpetrators -- perhaps his maternal grandfather or his biological father.

"They're got to choose" what happened to the boy, Townsend said during a hearing over what evidence and testimony will be brought into court.

A little more than a year ago, a Dakota County grand jury indicted Hokanson on three counts of first-degree murder and three counts of second-degree murder during acts of child abuse or neglect.

He had been arrested on June 27, 2009, four days after Nicholas stopped breathing on a picnic table, where Hokanson and his own mother had tried to revive him as an ambulance was on its way. He was pronounced dead at a hospital in Durand, Wis.

Dakota County sheriff's deputies questioned Hokanson. Court documents say he admitted shaking Nicholas 15 or 20 times and squeezing him at the home of his wife's parents, on a farm in Greenvale Township.

Hokanson had been mad at his sister-in-law when he shook the tot, he told investigators, court papers say.

An autopsy report documented multiple injuries of various ages, including bruises to the skin, scalp and muscles, cuts to the mouth and tongue, multiple rib fractures, and a fracture of a vertebra in the middle of the back.

The child had what a doctor called the worst spinal break he'd ever seen. His ribs broke after his rib cage allegedly was squeezed with such force that the fronts of the ribs were pressed to the backs.

The experts said those injuries caused his lungs to fill with fluid, which the state maintains killed Nicholas. The examination also found that his brain had been bleeding.

Public defender Lauri Traub told the judge that the state has to pick who did this, and "they got it wrong."

She pointed to two instances, including one close to the time when Nicholas died, when his biological father was reportedly seen shaking Nicholas' sister.

Townsend, however, said Hokanson was the only one who admitted shaking Nicholas, his stepson.

Hokanson also is accused of breaking the posterior rib of Nicholas' younger brother, Noah Hokanson, when he was 2 weeks old.

Traub said the boys' maternal grandfather, Charles Ohmann, has admitted that he slapped Nicholas' mother when she was a teenager.

"Sometimes you have to beat on them," Ohmann told investigators, adding that he, too, was beaten while growing up.

Joy Powell • 952-882-9017