CHICAGO (CBS) — Families of murder victims on the South Side bent the ear of the chief of detectives of the Chicago Police Department for a while Saturday at a forum at St. Sabina church.

They want closure. Patty Barnes lost her daughter Brittany in May 2009. The 21-year-old was one of four people shot in the Roseland neighborhood at a party. She says she’s frustrated because police think they know who did it but, witnesses won’t talk.

“The night that it happened, it was like over a hundred and some people there, but nobody won’t say anything,” Barnes said. “That is just so terrible.”

Chief of Detectives John Escalante says that is a common problem, but they keep working cold cases and many of them will be solved.

“Sometimes it’s reluctant witnesses,” Escalante said. “Sometimes it’s evidence that is uncovered late in the investigation. Sometimes it is lack of cooperation, not just from witnesses but sometimes even from family. That’s rare, but sometimes that happens.”

Escalante had people attending the forum fill out questionnaires and assured them detectives would be looking at their cases again come Monday.