Dale Jankowski said Thursday he didn't have any indication his 70-year-old mother planned to gun down his ex-wife outside a preschool last week.

"There was some behavioral changes that took place that I attributed to old age or something else, I don't know," said Jankowski. "I had no idea that she was going to do anything like this."

Prosecutors have charged Mary Nance Hanson with first-degree murder in the death of Jankowski's ex-wife, 34-year-old Tetyana Nikitina. Charging documents filed Thursday in 3rd District Court say Hanson shot Nikitina four times in the head in front of dozens of witnesses last week at Salt Lake Community Action Program Head Start, 336 E. 3900 South.

Nikitina had been a preschool teacher at Head Start for two years and was the mother of Jankowski's children: Stefan, 7, and Aleksandra, 9.

Jankowski said Thursday he is grieving the loss of his ex-wife, whose funeral was held Wednesday. His children are struggling to understand their mother's death, he said.

"They do well sometimes, but this morning on the way to school, Aleksandra started crying. I asked her what was wrong and she said, 'I miss my mommy,'" said Jankowski.

Jankowski said he is planning an additional memorial for Nikitina so his children can be more involved in saying goodbye to their mother.

Charging documents say Hanson, who wore a gray hoodie, walked up to Nikitina's vehicle and began shooting, according to witnesses. At one point, she appeared to reload the gun, charges state.

Unified Police Department officers who arrived at the scene found Hanson in the parking lot where the shooting occurred and arrested her. Nikitina's body was slumped over her steering wheel, charges state.

Divorce documents filed by Nikitina show she had a strained relationship with Jankowski and his mother. The couple argued over custody of the children in divorce papers, each accusing the other of kidnapping the children at different points.

Nikitina, a native of Kiev, Ukraine, cited a difficult relationship with Hanson when she filed for divorce from her husband of seven years in 2005. She called Hanson "verbally abusive" and claimed the woman had a history of psychiatric issues and being "overbearing and controlling of her children."

Jankowski declined to speak about the psychiatric issues Nikitina referred to, deferring questions to police.

"They're investigating that whole thing. There have been a number of accusations here or there. I don't want this to be a public trial," he said.

If convicted, Hanson may be sentenced to prison for 15 years. An initial court appearance had not yet been scheduled for Hanson as of Thursday afternoon.

The Unified Police Department on Monday served a search warrant at Jankowski's Taylorsville home. Department spokesman Lt. Don Hutson said Thursday so far there is no evidence Jankowski is connected to the slaying.

Jankowski, meanwhile, said he is focusing on the good memories of his wife, despite the couple's bitter divorce. He said he met Nikitina through a friend who knew her sister. The two talked on the phone and corresponded through letters for a while, until Jankowski decided to fly to the Ukraine to meet Nikitina in person. After spending three weeks together, the couple decided to marry and moved to the U.S., he said.

"Absolutely, I'm grieving her loss. She must have gone through terror when [the shooting] occurred. No one deserves that," Jankowski said.

He said he has seen his children cry "too much" in the past several days.

"When they cry, I cry," he said. " The children are going to miss out on so much [without their mother]."

Jankowski said he hasn't spoken to his mother since the shooting and doesn't plan to visit Hanson anytime soon. Hanson remains in the Salt Lake County jail. Bail is set at $1 million.

mrogers@sltrib.com