A New York City student from China who prosecutors say plunged into the dark side of the Internet was sentenced Tuesday to 16 years in prison for trying to acquire ricin so he could sell "simple and easy death pills."

Cheng Le, 22, was sentenced in Manhattan federal court after his conviction by a Manhattan jury in August on charges he tried to acquire ricin as a weapon, postal fraud and identity theft. Ricin is a fatal toxin with no known antidote. The sentence was within the range suggested by federal sentencing guidelines.

Judge Alison Nathan said the "horrible, serious and quite terrifying offense" required a severe sentence, but she added that no one was harmed by the plot because Le's communications were intercepted online by investigators who found him in an area of the Internet where criminal marketplaces thrive.

Among evidence introduced at trial were statements Le made in writing about getting ricin from an FBI covert employee, including: "If you can make them into simple and easy death pills, they'd become bestsellers."

Le was arrested in December 2014 after prosecutors said he contacted an FBI covert employee online using an encrypted messaging service and asked if he sells ricin. Authorities said Le was wearing latex gloves when he went to a postal office to retrieve a fake shipment of pills.

Patrick Brackley, Le's lawyer, urged leniency, citing a letter from Le's parents describing his immaturity when he came to the United States to study physics at New York University. The lawyer said Le had received offers from several Ivy League schools.

Assistant U.S. Attorney Ilan Graff called Le's crimes serious, troubling and chilling.

"The defendant sought to profit from murder," he said.

Le said he lives with regrets.

"Not a day goes by where I don't think of all the things I could have done," Le said. He dabbed his eyes with tissue several times in court before he was led away in shackles.