02/02/2012 03:36 pm ET

Lane Bryant Murders: Four Years Later, Slaying Case Unsolved (VIDEO)

Thursday marks the four-year anniversary of a botched robbery attempt at a Tinley Park, Ill. Lane Bryant store that left five dead and one injured, a crime that remains unsolved.

On Saturday, Feb. 2 2008, a man entered the suburban Chicago retail store about 10 a.m. and announced that he was armed. He reportedly bound the six women in the store--the store manager, an employee, and four customers--with duct tape in a back room. Shortly after store manager Rhoda McFarland freed herself and called 911, the purported robber shot all six women, execution-style.

The incident continues to shake the Tinley Park community and surrounding neighborhoods because police have yet to identify a suspect in the killings, ABC Chicago reports. The sole survivor provided investigators with a description of the gunman, which police say prompted more than 6,000 tips on the case, but no arrests have been made.

Tinley Park Police Commander Pat McCain says that investigators are still working actively on the case, and 137 new tips were submitted in 2011, WLS reports.

"The thing is, somebody knows," McCain told WLS. "The Palatine thing went on for nine years before somebody came forward."

McCain was referencing a similar botched robbery in nearby Palatine in 1993, where seven people were found murdered in a Brown's Chicken and Pasta restaurant. The case was cold for nine years before one of the attackers' ex-girlfriends came forward.