A 12-member jury — 10 women and two men — found an 18-year-old Blue Earth man guilty Wednesday of possessing explosive components with the intent to make a bomb.

After six witnesses had testified, John Andrew Yahnke took the stand on his own behalf and told jurors, “I was not making a bomb.”

During the one-day trial, Yahnke’s attorney — public defender Bill Grogin — says the state’s case hinged on a 15-year-old girl’s statement that his client told her to stay out of the kitchen in his apartment because he was making a bomb.

“She is definitely mistaken in what she heard. We all make mistakes,” Yahnke told the jury, adding that he did not think the girl was lying.

He says loud music that was playing while several friends gathered and talked in his apartment on July 9 would make it easy to misunderstand someone.

“I think it’s unfortunate my client was convicted because of the inconsistent statements of a 15-year-old girl,” says Grogin, adding she changed the story she originally told police.

The girl testified that when she and a friend visited Yahnke she saw him taking fireworks apart in the kitchen and also saw fireworks in his bedroom.

She says he asked them if they had a checking account so he could buy “some stuff” to make a bomb.

“I took it serious,” says the girl.

Under cross-examination, Faribault County Attorney Brian Roverud asked Yahnke if he remembered writing a letter to a friend in which he wrote: “I finally figured out who told on me. It was A.I. I have statements from her, she narced on me.”

However, Grogin says in the letter his client asks for support from his friend because he is “an innocent man.”

“I can’t believe this is happening to me …. I was never making a bomb. You’ve got to believe me,” the public defender says his client wrote to his friend.

Following testimony of witnesses totaling almost three hours, jurors deliberated about one hour to return with a guilty verdict.

“The evidence may have been circumstantial, but it was a good indication of what he (Yahnke) was thinking and intending to do,” Roverud says of the jury’s decision.

Grogin would not comment if his client plans to file an appeal.

“I will talk with him on whether he wants to make an appeal. If so, I will put him in touch with the appropriate office,” he says.

In convictions involving public defenders, cases are sent to the State Public Defender Appeals Office to determine if an appeal will be made.

Yahnke was arrested on July 14 after authorities executed a search warrant at his residence at Crescent Apartments in Blue Earth.

Officials confiscated two 5-pound plastic bags labeled ammonium nitrate and one 10-pound bag labeled sodium nitrate. Other items seized included five Black Cat Blooming Flowers, Jumbo Crackeling Balls, cardboard cylinders, two model rocket engines and igniters, wooden dowels, fuses, ionized salt and 75 miscellaneous legal fireworks.

Yahnke says he intended to use the items to make model rockets, but he gave up because he didn’t have the equipment, materials or the money. He says the ammonium nitrate and sodium nitrate cost him $60-$70, so he kept the chemicals in case he decided later to build a rocket.

In his opening statement, Roverud told the jury, “I want to make a bomb. That’s what John Yahnke said to a witness.

“You’ll hear evidence that these items could be put together to manufacture an explosive device,” Roverud added.

Grogin told jurors any of the items found in Yahnke’s apartment were legal and could be purchased at some stores. He says the prosecution was trying to create a crime.

“John Yahnke was not building a bomb. He never intended to build a bomb. He never told anyone he wanted to build a bomb.“

“They (police) did not find a bomb, did not find directions of how to build a bomb, and did not find a partially built bomb,” says Grogin.

It was the girl’s mother who notified police after being told of the incident nearly a week later.

In his testimony police officer Jake Ruppert says he requested a search warrant right away because the situation was serious.

Grogin asked the officer why he did not seek other witnesses before obtaining a warrant.

“My main concern was how far along the bomb was. I really didn’t know what was going on,” Ruppert says.

The officer says he did interview two other people who also said fireworks were being taken apart in the kitchen.

When local authorities found the plastic bags of white substance, Ruppert says, Police Chief Dean Vereide contacted the Minnesota Duty Officer.

The Minnesota Bureau of Criminal Apprehension then dispatched the Chemical Assessment Team (C.A.T.) of Mankato, Bloomington Bomb Squad and Bureau of Alcohol, Tobacco and Firearms to the scene.

Glen Cansler, a member of C.A.T., testified the white substance was evaluated at the scene and found not to be dangerous in its current state. He says the building was not evacuated, but residents were told of the situation and they could decide if they wanted to leave.

Cansler says the materials were determined to be as labeled and then packaged in sterile jars so they could be tested at the BCA laboratory.

In a two-page report, BCA forensic scientist Kristin McDonald says she found the substances to be ammonium nitrate and sodium nitrate.

McDonald testified three components are necessary to make an explosive — an oxidizer, a fuel and something to ignite it.

She says ammonium nitrate or sodium nitrate would act as an oxidizer.

As for the fuel, it would need to be carbon based, McDonald says, such as sugar, wood chips or powdered metals. She says fireworks contain flash powder, which have powdered metals. To ignite the device engines from model rockets could be used, she adds.

“As far as building an explosive device, is there anything missing?” Roverud asked McDonald.

“No. There is not,” she answered.

Yahnke says he was surprised to hear McDonald say model rocket engines could be used to make an explosive device.

A teen friend testifying on behalf of Yahnke says the two shared a love for fireworks.

He says he saw Yahnke emptying powder from fireworks onto a piece of paper about the size of a golf ball. But, he didn’t think it was illegal or dangerous.

When ignited, it would cause “a very bright flash,” says the teen.

When questioned by Roverud, Yahnke admitted purchasing the materials at different places, including out of state.

“In buying and using these, did you ever think you were doing anything wrong?” Roverud asked.

Yahnke replied he did not.

He remains in custody at the county jail and will be sentenced once a pre-sentence investigation is completed.

Conviction of possession of one or more components with intent to manufacture an explosive device carries a maximum penalty of five years in prison and a $10,000 fine.