Exit: Theft on the Mississippi

You're a team of investigators traveling the Mississippi on a paddle-wheel steamboat in 1872. Last night there was a robbery. A successful businessman was carrying documents of inestimable value, and now they have disappeared! The captain has asked for your help in finding out who did it, but time is running out. Can you find the culprit before the riverboat docks in New Orleans and the thief escapes into the night?