MILWAUKEE, Wis. (WTAQ) - A concrete panel that fell from a downtown Milwaukee parking ramp and killed a teenager might not have been as strong as the original design called for.

The Journal Sentinel said 2 steel connections instead of 4 were used to attach the decorative panel to the outside of the O’Donnell Park structure. And investigators are trying to determine if the steel was as strong as the design specifications required.

Investigators have been X-raying the 13 ton slab that fell from the second floor of the ramp on June 24th. It killed 15-year-old Jared Kellner of Greenfield, who was heading to the nearby Summerfest. 2 others were injured.

Authorities say it’s not clear if a change of design would be a possible cause of the incident. It’s also not known whether Milwaukee County took steps to prevent moisture from corroding the joints that connect the panels to the walls.

The sheriff’s department and the district attorney’s office are heading up the investigation. County Executive Scott Walker says the 17-year-old parking ramp may never re-open if it’s determined that the problems with the panels are widespread, and repairs would be too expensive. He said he doesn’t want to take a chance that another panel may fall.