A current story in The News & Observer makes a passing reference to a "prison trustee." I thought the term was "trusty." So I checked online first and found this reference in the Columbia Guide to Standard American English. Then I checked the Associated Press Stylebook. Indeed, a trustee is a "person to whom another's property or the management of another's property is given," the stylebook says. A trusty is "a prison inmate granted special privileges as a trustworthy person."
I wonder if correction department lingo has changed over the years or if it's just a matter of mixing up two spellings. I did a quick search of the N&O's archives since 1990 and found a few references to "prison trusty." One story in our archives from The Fayetteville Observer about the Cumberland County jail has this passage:
"We refer to them as 'inmate help,' not trusties," said Deputy Sheriff John McRainey, the chief jailer. "We don't use the term 'trusty' any more."
"In here, we don't trust anyone," he said. Though McRainey smiled, his tone affirmed that he wasn't kidding.