CHICAGO (CBS) — She lost her life over an iPhone at a CTA train stop. CBS 2’s Suzanne Le Mignot has exclusive new details about what led police to Sally Katona-King’s possible killer, a teenager who is being questioned in the case.

Police have been questioning a teenager in Katona-King’s death in March, when a robber pushed her down the stairs at the CTA Red Line’s Fullerton station after he had stolen someone else’s iPhone.

Sources said that witnesses to the crime and DNA evidence are what may lead to murder charges against the teen, who was already in custody for another iPhone robbery at a different CTA station.

“I hope that evidence will be helpful to convict him, if he’s the correct person,” said Katona-King’s friend, Pastor Eardley Mendis of First Lutheran Church in Logan Square.

Katona-King, 68, worked at First Lutheran Church in Logan Square, where she cooked for the homeless and was the church treasurer.

Sources said the teen being questioned in her death was positively identified by witnesses as the person who stole an iPhone from a woman at the Fullerton CTA stop on March 28. Witnesses said that, as he was running away, he pushed Katona-King down the stairs. She later died from her injuries.

“To just push an older lady down a set of stairs or just to push her down, to me, that’s just a whole different frame of mind,” said Katona-King friend Jim Blaha. “If they realize that there’s consequences for these actions and that’s why I hope that there is justice served. So people need to learn, that they can’t get away with doing things like this.”

Sources said the 17-year-old is currently serving time for a similar iPhone robbery that took place in Chicago. In that incident and the Katona-King case, sources said the teen left items behind at both scenes. DNA tests were underway on those items, to determine if the teen is linked to Katona-King’s murder.

“Family members are very sad. I occasionally see them. So, it will be good for everyone to have a closure,” Mendis said.

Close family friend Bill Lambe also said that closure is very important for the family, especially for Katona-King’s grandson. Lambe said it means a great deal that police are still working on the case and Katona-King is not forgotten.

Katona-King’s family members could not be reached for comment on Tuesday.