Eran Ribak just does not understand how Representative Anthony D. Weiner could not recognize whether the man in the gray boxer briefs was him or not.

“I know every photo I have on my computer, and he should know every photo he has on his computer,” said Mr. Ribak, 34, who owns a produce market in Sheepshead Bay, Brooklyn, in Mr. Weiner’s Congressional district. “I make sure I don’t upload to my computer any photos I think are indecent, because anyone could log on and send them out.

“As a congressman, he should know better.”

Mr. Ribak waved his cellphone to show off a picture of his 2-year-old son, Josh.

“I know exactly when it was taken,” he said, as if to prove his point. “Last year at the park.”

Last weekend, a suggestive photo was sent from Mr. Weiner’s Twitter account to a 21-year-old college student in Seattle. Though Mr. Weiner quickly took the picture down, saying his account had been hacked, the picture was spotted and publicized by a conservative blogger, attracting national attention, and, after days of confusing statements, Mr. Weiner told MSNBC on Wednesday that while he had not sent out the message containing the photo, he could not “say with certitude” that the picture was not of him.