WASHINGTON — The Georgetown University sophomore who made ricin in his dorm room in March has pleaded guilty to a federal offense.

Dan Milzman, 19, who was partly inspired by the HBO series “Breaking Bad,” pled guilty to a charge of unregistered possession of a biological substance. It was part of a plea agreement which includes prison time anywhere from 1 to 2 years. After, he would has three years of supervised release.

Sentencing is scheduled for Nov. 10.

Milzman learned to make the deadly toxin from online sources and by watching his favorite T.V. show, “Breaking Bad.” He’s accused of purchasing the ingredients from local stores, including Home Depot and American Plant Food Company.

A Georgetown resident adviser told investigators Milzman tossed a double- sealed plastic bag of the grayish powder at his feet. The FBI says laboratory testing indicated the substance was ricin and capable of killing.

Follow @WTOP on Twitter and WTOP on Facebook.