Chicago ? Authorities tried Tuesday to determine how a man who called himself “Dr. Chaos” obtained cyanide and stashed it in a closet of the city’s mass transit system, locking it to protect the potentially lethal chemical.

Joseph Kon-opka, 25, was in federal custody, charged with possession of a chemical weapon. Investigators in Wisconsin, where he is charged in a five-county rampage of vandalism, said Konopka was an anarchist who had the “propensity to commit mass destruction.”

While no one was hurt, some security experts say Konopka’s ability to stockpile deadly chemicals and get his hands on keys to subway passages makes the danger clear.

“You get some lone nut out there, whether they are passing cyanide around or botulism or any … harmful bacteria, as long as they are not contacting anybody, that is going to be hard to find,” said former FBI agent Dick Skilling, now a consultant for a Chicago security company.