Sometimes defendants may be difficult to locate. Helpful information sources include which of the following?

A) Telephone directories
B) State and county tax rolls
C) Former fellow workers
D) All of these choices are correct.

All of these choices are correct because telephone directories, state and county tax rolls, and former fellow workers can all provide valuable information that might help in locating a defendant. Telephone directories can offer current or past addresses and phone numbers, state and county tax rolls can reveal property ownership and addresses, and former fellow workers might have personal knowledge about the defendant's whereabouts.