Martin Kamen

Jeopardy: "Disheveled after days of work leading to the discovery of this carbon dating isotope, Martin Kamen was detained by suspicious police." What is Carbon-14? Quite obviously, of course, but that is clearly not the most interesting part of this answer.

That much is true: on February 27, 1940, Kamen emerged from the lab at UC Berkeley after finally succeeding in isolating the important isotope. (He often gets most of the credit, but we have to honor his partner, Sam Ruben, a fellow Jew.) His disheveled appearance was not up to the norm for the prim 1940s... especially that three-day beard. So the police detained him, because they thought... Wait for it... wait it for it...

They thought he was a serial killer!

Apparently, an escaped convict has been roaming the Bay Area, killing people. All it took was some red eyes and extreme facial stubble for Kamen to be declared a suspect. Thankfully, he was quickly released, as witnesses placed him in the science lab. Nerd, not murderer.

All of that pales in comparison to later in life, when US authorities erroneously believed that Kamen was a Soviet spy... Seriously, can't a man just do science in peace?