John James didn't realize he had left more than $100,000 of jewelry and other valuables in the back seat of a taxi until he reached for his bag to show off the treasured photographs he'd taken with a few of his late friends: the actress Sylvia Sidney, writer Dominick Dunne and broadcaster Alistair Cooke.

Mr. James had just returned to his apartment Sunday afternoon from an office near Madison Square Park, where he'd picked up a tote bag holding the photographs, just over $200 in cash and the jewelry. He said he planned to...