Wiktionary
n. (context now chiefly historical English) Someone whose job it is to find and capture thieves.
Wikipedia
In English legal history, a thief-taker was a private individual hired to capture criminals. The widespread establishment of professional police in England did not occur until the 19th century. With the rising crime rate and newspapers to bring this to the attention of the public, thief-takers arose to partially fill the void in bringing criminals to justice. These were private individuals much like bounty hunters. However, thief-takers were usually hired by crime victims, while bounty hunters were paid by bail bondsmen to catch fugitives who skipped their court appearances and hence forfeited their bail. Both types also collected bounties offered by the authorities. Sometimes, thief-takers would act as go-betweens, negotiating the return of stolen goods for a fee. However, they were often corrupt themselves, for example extorting protection money from the crooks they were supposed to catch. Government-funded rewards for the capture of criminals were a corrupting influence, leading directly to the Macdaniel scandal.
Usage examples of "thief-taker".
Not that I made it that difficult, but the thief-takers have been alarmingly obtuse during my short, colorful career.
The voice of Peter speaking in anger was not likely to be unheard, and the stern mandate had scarcely issued from his lips, when a dozen of the common thief-takers of Vaud set about the affair in good earnest, and with the best possible intentions to effect their object.
But what I think she said to me was as how there was a thief-taker who'd grabbed holt of her son, sayin' as how the boy was one o' the ruffians who broke up Hillsborough, and meanin' to take him to the gaol in New Bern.
I have no choice but to lodge an information with the thief-takers at Erze Damath!