The Minneapolis Police Department disclosed Friday that they discovered a backlog of 1,700 untested rape kits from the past three decades, The Star Tribune reports. Chief Medaria Arradondo reportedly didn’t explain why the force sat on the rape kits for so long, or why the kits weren’t reported in a 2015 audit—which said only 194 rape kits had gone untested. The department’s Sexual Assault Unit is still conducting a final count of the kits, which were first discovered in July. “I very honestly stand before you to say we still don’t know why that (miscount) did occur back in 2015, but moving forward I can ensure you that it will never happen again,” Arradondo told reporters at a news conference. Deputy Chief Erick Fors estimated that it would take about two years to get all of the kits tested. “The culture has changed, and we have an obligation to test these kits,” Fors said. “Hopefully this will not only result in people getting justice, but this is a debt that we owe.”