World Health Organization
U.S. Department of Defense
|Family||Fran Swinton (wife)|
|First Appearance||"A Person of Interest"|
Croydon studied at Strathcona University but failed to conclude his thesis and never earned a PhD, although he included it in his later resumes. In 1988, while working as a scientist for the Defense Department, he wrote a letter denouncing American companies exporting anthrax to despotic regimes. He sent it to an editor and, as a result, got reprimanded. In the early 90s, he worked at the Army bioweapons lab at Fort Detrick. He then moved to Bendigo, Australia to investigate an anthrax outbreak.
In the late 90s, he moved to South Africa, on behalf of the World Health Organization, to study anthrax. Around this time, his wife, Fran, moved back to New York with her son to deal with her diagnosed breast cancer. Croydon completely neglected his family and instead kept focusing on his work as a mean, according to him, to save his country. He divorced from his wife thereafter and later found work at Haznostics Incorporated, a New Jersey-based testing facility for environmental hazards and bioagents.
A Person of Interest
Croydon was unknowingly manipulated by criminal mastermind Nicole Wallace, who wanted her vengeance upon MCS detective Robert Goren and had previously known Dan while being in Australia. She linked him, with false clues, to a stolen south African anthrax vial and some anthrax vaccine boosters. It was all planned to make it appear as if Croydon was plotting to attack government facilities with anthrax-laced letters, his motive being both his need to demonstrate his theories regarding national security and his resentment towards government, that had previously silenced him.
As Wallace had foreseen, Goren fell into her trap and focused his inquires uniquely upon Croydon (also because he reminded him of his egoistic and neglectful father), putting him under pressure by publicly sustaining his status as a "person of interest" in the investigation and confronting him at a press conference. Croydon, exhausted, was convinced by Nicole into writing a letter where he accused Goren of ruining his life and proclaimed his innocence. He was ultimately killed by Wallace, who faked his suicide in order to further discredit Goren and making him believe he had indirectly caused Croydon's death. Nicole later placed the anthrax vial and the vaccines on a train for Montreal, in order to prove Croydon's innocence and complete her plan.