The jailer treated his prisoners as dangerous criminals. His treatment may have reflected his own attitude more than the seriousness of their alleged crimes. [source][source][source]
"Jailers commonly were retired army veterans, who could be expected to follow orders and use their military skills as required." [1][source]
"He was no mere turn-key, but the governor of the prison,-probably of the rank of a centurion, like Cornelius at Caesarea, of whose history there is much to remind us here." [2][source]
"If Lydia came from the top end of the social scale and the slave girl from the bottom, the Roman gaoler was one of the sturdy middle class who made up the Roman civil service; and so in these three the whole gamut of society was complete." [3][source]