Dr. Olga Duchon, 42, of Vernon Hills spoke to a Ukrainian medical association in Wheeling Sunday afternoon before visiting the townhome in Barrington.
About 5:40 p.m., police were called to the home in the 400-block of West Russell Street.
Duchon had been shot in the chest.
She died at a nearby hospital soon after.
"It was very shocking," neighbor Alex Paretes said. "It doesn't happen in Barrington; it's very odd."
Police were seen taking a man into custody outside the home Sunday night.
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Officers also apparently removed a child from the home.
Neighbors said the man who lives there shared a 2-year-old daughter with the woman who was killed.
A neighbor who lives next-door said she never heard a gunshot, but did hear the cries of a toddler.
"My husband heard, I'm pretty sure it was their daughter crying and upset, which we usually don't hear much. And he thought that was odd. And then shortly after, the police started showing up," neighbor Juliana Etling said.
Barrington police classified the shooting as a domestic-related incident, and said the general public is not at risk.
Barrington police say the investigation is continuing.
They did not confirm whether anyone remains in custody, and, at this point, they have filed no charges in the case.
The Cook County Major Crimes Task Force is also investigating.
You can contact the Illinois domestic violence hotline at 1-877-863-6338 click here for more information.