A State Police report says a drone that sneaked contraband into a Michigan prison in May went undetected for nearly two months.
Michigan Department of Corrections spokesman Chris Gautz says video surveillance shows that inmates at Richard A. Handlon Correctional Facility received two packages dropped by a drone May 29.
Prison officials suspect the packages contained cellphones that were found inside the prison in July.
The report, which was obtained by the Detroit News through a Freedom of Information Act request, says a third package containing contraband was delivered that day, but prison officials recovered it.
Gautz says the Corrections Department didn't previously disclose the successful drone drops because they "don't discuss all introductions of contraband."
He also says officials weren't certain the confiscated phones were delivered by a drone.
The prison had two attempted drone drops in August.
Prison officials apprehended the packages in those attempts.