The student, Daniel Harry Milzman, made the white powder with materials he bought at local stores, including The Home Depot and American Plant Company, according to an affidavit filed in court on Thursday. He found the recipe for making it by doing a search on his iPhone, investigators said.
Wearing goggles and a dust mask for protection, Milzman used Epsom salts and castor beans, among other materials, to make the ricin in his dorm room about a month ago, according to the affidavit. He stored what he had made in plastic bags sealed with hockey tape.
On Tuesday evening, for reasons that are unclear, Milzman showed some of his ricin to his residential adviser, who promptly contacted the university's counseling services, who, in turn, called the police, the affidavit said.
Milzman described his efforts during an interview with FBI agents later that day, the affidavit said. A federal laboratory tested the contents of the bags and confirmed that they contained the ricin toxin.
Milzman remained in custody Friday evening, pending a hearing on March 25, Jacqueline Maguire, an FBI spokeswoman, said. She said that the law enforcement agency did not believe Milzman had a connection to terrorists or to a terrorist plot.
Danny Oronato, a lawyer representing Milzman, declined to comment on the case.
Georgetown University said in a statement on Wednesday that no one had been found suffering from exposure to ricin, and that it had paid contractors who specialize in dealing with biological hazards to clean Milzman's room.
"There is no immediate threat to members of the Georgetown community," the statement said.