unsub
n.— «Unsub is shorthand for “unknown subject,” meaning the person believed to have committed the crimes. Nor is it new. There was a 1989 series called Unsub, which followed a government unit investigating serial killers.» —“‘Unsub’ unmasked and other TV queries” by R.D. Heldenfels Akron Beacon Journal (Ohio) Apr. 6, 2006. (source: Double-Tongued Dictionary)
Further reading
Enthusiastic book recommendations! Martha’s savoring the biography of Alexander von Humboldt, the 19th-century explorer, polymath, and naturalist who revolutionized our understanding of nature and predicted the effects of human activity on...
We use the term Milky Way for that glowing arc across the sky. But how people picture it varies from culture to culture. In Sweden, that starry band goes by a name that means “Winter Street,” and in Hawaii, a term for the Milky Way...