Sherlock Holmes solved many a mystery, but his exploits don't compare to the patience and persistence required by genealogists trying to identify old family photos. I've spent four years analyzing readers' picture puzzles for the Identifying Family Photographs column on this site and the Photo Detective column in this magazine. Although I haven't cracked every photographic code, I have put names to dozens of unfamiliar faces.

Successful identifications result from partnerships: Readers supply their family data, and I sort through the clues. Faithful readers know it's possible to identify a picture based on their knowledge of family history and attention to photographic details, such as image type, photographer's imprint and costume clues.