dropped off 64 grams of marijuana and 6.6 grams of marrow win mayo heroine in the ris on that yard at mansfield correctional institution. in south carolina, doyle oig sentenced to 15 years for trying to fly a drone into this maximum security prison. and this drone crashed in january, attempting to smuggle nearly 7 pounds of crystal meth across the u.s./mexico border. >> i think law enforcement at large is concerned drones will be used to deliver things that they shouldn't be delivering or they might be used by drug dealers and even a concern would be that at some point people might use these to drop explosives or things like that. >> reporter: about 700,000 drones are expected to be sold this year. and it's predicted drone sales will reach 1 million by 2018. in july, the department of homeland security warned law enforcement agencies around the country about the potential danger of growns in the hands of criminals. >> this is a no-brainer. we don't want unauthorized access to prisons by anyone under any means with any technology. and i think until it becomes a big enough issue, you will continue to see the problem. >> well, technology to intercept