Federal prosecutors claim Charlie Tan ran a business selling drugs on campus at Cornell University, before the killing of his father in 2015.

“Tan’s phone records confirm that he sold marijuana to other students (charging $200 an ounce), had received a 5-pound shipment of marijuana from California for $12,000 in January of 2015, and that he also sold psilocybin mushrooms, and DMT, both of which are psychedelic drugs,” according to a new court filing by U.S. Attorney Lisa Fletcher.

The new paperwork filed by federal prosecutors is in response to the defense’s argument last week that Tan should only serve five years in prison on federal gun charges.

Tan will be sentenced Nov. 19. He pleaded guilty to the charges back in June, but did not admit to shooting and killing his father Liang "Jim" Tan — CEO of Canandaigua-based Dynamax Imaging — at their Pittsford home in 2015. In a character letter filed last week, Tan said "I felt like there was no other option."

“He was old enough, mature enough, and smart enough to understand and appreciate the gravity, and ramifications, of murder. And this murder was not impulsive. The defendant devised a plan, and took great steps to carry it out,” federal prosecutors say.

Federal prosecutors argue Tan should serve 25 years in prison.