To write to an offender, you need the offender's name and DOC number and the name and address of the correctional facility where they are housed. You can look up an offender's DOC number and location on the IDOC website at http://www.in.gov/apps/indcorrection/ofs/ofs. IDOC correctional facility addresses are also available online at here.
Address both the letter and envelope as follows:
Offender name, DOC#
Street Address or PO Box
City, IN ZIP code
All incoming and outgoing mail is opened, examined, and read by designated facility staff. For more information about offender correspondence and restrictions see Policy 02-01-103 Offender Correspondence (http://www.in.gov/idoc/files/02-01-103__8-17-09.pdf)