Detroit Police said a bags of drugs from a 4-year-old case were accidentally displayed during a news conference intended to showcase the results of a recent seizure.
Bags full of pink, yellow and green Ecstasy pills were displayed with evidence tags showing the date of 9/8/08.
Sgt. Eren Stephens told The Detroit News, "it was a mistake" but most of the drugs display Thursday were from the recent confiscation.
Stephens said someone "accidentally grabbed evidence from another case."
Chief Ralph Godbee and narcotics officers showcased the drugs for the media from a bust they said amounted to more than $1.3 million worth of illegal drugs and weapons.
Officers also confiscated a number of firearms during the bust. They included long guns, handguns and assault-type weapons.