We're sure of that," Escalante said in the news conference just outside the 47th Street station.
Family members identified the woman as Jessica Hampton, 25.
A woman was stabbed to death and a man was taken into custody Thursday in a midday attack on the CTA Red Line that police described as a domestic dispute.
The fatal attack, a rarity on CTA trains, prompted passengers to flee, screaming in horror, a witness said.
With bus-stop crimes included, overall crime showed a 23 percent decrease in 2015 over the previous year.