Though police already have a detailed confession from Pedro Hernandez, the alleged killer of Etan Patz, they took the unusual and melodramatic step of having him sign a photograph of the child, an image that has kept the case in the public mind for 33 years.

As The New York Times' Joseph Goldstein reports, the signature and a scrawl of "I killed him" or "I strangeled him" across the iconic photo of the missing boy "may emerge as one of the more memorable courtroom exhibits if the case goes to trial, especially since the prosecution is likely to lack physical evidence tying Mr. Hernandez to the crime." While Hernandez has given details of how he allegedly killed Patz, he hasn't offered a motive, and police haven't found a body (and probably won't) -- two crucial components of most murder investigations.

The extra step of having Hernandez sign the photo speaks to the power Patz's image has exerted in keeping his disappearance on people's minds as his case lingered for decades. Etan's father, Stanley Patz, took the photos that would go on to be the first of a missing child to show up on the side of a milk carton. And in 1983 Ronald Reagan deemed May 25, the date of his disappearance National Missing Children's Day. Author Anna Quindlen, who was a Times reporter covering Etan's disappearance in the 1980s, recently told The New York Observer's Ben Weitzenkorn: "There’s probably no little boy who’s ever been photographed in history who is as alive in the frame as that child is in those photographs."