Jeremy Ryan, 30, has been charged with attempting to posses radioactive material with the intent to kill someone, according to court documents.
The complaint says Ryan was trying to purchase radioactive material online to kill an unnamed individual. The potential seller of the material was actually a covert F.B.I. agent.
Ryan was arrested when a package, containing an inert substitute for the material, was delivered to a Madison address and claimed by Ryan. He was arrested in Black Earth, Wisconsin on Wednesday.
If convicted of the crime, Ryan faces a maximum penalty of life in prison.