On Wednesday, one highly-anticipated witness took the stand.
Leuthold is accused of killing his wife Denise by shooting her in the head, then staging a home break-in.
It all happened on Valentine’s Day last year at her parents' home on Mossville Road.
The State's Attorney says Nathan Leuthold's love for another woman was the motive for the crime.
That woman, they say, is Aina Dobilaite.
Nathan and Denise Leuthold were Aina's student sponsors.
She's studying in the U.S. from Lithuania and met the Leutholds while they were in her home country doing mission work.
The Lithuanian woman was granted immunity in exchange for her testimony.
Aina Dobilaite explained to the jury that she met the Leutholds when she was only 6 years old.
She described Nathan Leuthold as her sponsor, a role-model, even someone she worked for.
But she still denies any romantic connection.
“Here in America he was the only person with whom I could talk in Lithuanian, so he was a friend,” Aina said.
But State's Attorney Jerry Brady still finds that hard to believe.
“You have told Nathan Leuthold you love him correct?” Brady asked. To which Aina replied “No.”
Brady also had an email he says Nathan Leuthold sent Aina less than a month before his wife, Denise, was murdered.
Aina says she doesn't remember receiving it, but Brady had her read it.
“You deserve someone who respects you and puts their relationship first and from now on I want to do all that I can to be that person,” Aina read. “There's nothing more important to me than you and this relation. I'm so blessed to have you in my life and I know it.”
The prosecution team also refreshed Aina's memory on another email she says she doesn't recall.
This one, written from Aina to her mother before the funeral but after Denise's death.
“It might be quite difficult on Monday and Tuesday but after that it should be better,” Aina said about Denise’s death. “Children cried only once when they first learned about it. Janelle did not say once that she wanted her but she, if she needs anything, she asks for Aina.”
The defense team says that email is translated English and doesn't directly translate to those words.
But it took time getting Aina to speak English.
She also complained about the assigned interpreter not translating effectively.
But, Brady called her bluff.
“You've never had any difficulty with any of the 3 colleges you have attended in speaking or writing English correct?” Brady asked. “In fact you are proficient in written and spoken English isn't that correct?”
Aina replied, “Yes.”
Defense Attorney Hugh Toner continued highlighting that Aina and Nathan's relationship can't be proven to be anything but platonic.
When the prosecution brought up their join bank account, Toner crossed with the fact that she needed a joint owner because she did not have a social security number at the time.
Prosecutors granted Aina immunity in exchange for her testimony.
Other key witnesses included an inmate who claimed Leuthold confessed to the murder, the owner of a local spa owner that said Nathan and Aina frequented her business often, and other forensic experts.
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