Rep. Anthony Weiner says he cannot say for sure that the lewd photo sent on his Twitter feed is not him.
In an interview with MSNBC on Wednesday, the Democratic congressman was asked whether it was him in the photo, which was a close-up bulging groin shot.
"You know, I can't say with certitude. My system was hacked. Pictures can be manipulated. Pictures can be dropped in and inserted," he said.
Weiner, who has hired a lawyer, said he has asked a private firm to look into the matter and conduct a "forensic examination."
But the congressman and likely New York City mayoral candidate, who became irate on Tuesday when reporters pressed him about the photo, continued to insist the whole thing was a joke.
"We don't know exactly what happened here," he said. "It was a prank. It is not a national security thing. I'm not sure I want to put national federal resources into trying to figure out who posted a picture on Weiner's website of whatever."
"I'm not really sure it rises, no pun intended, to that level," he added.
The photo was posted on Friday and sent to a female college student in Seattle. It was quickly deleted, but a frenzy of coverage and comment ensued.
Weiner was a Twitter follower of the female college student who received the photo.
The tweet of the lewd photo first was reported Saturday by BigGovernment.com, a website run by conservative commentator Andrew Breitbart.
The site said the photo was tweeted to a female college student in Seattle. The woman told the New York Daily News that she had never met Weiner, and that there had "never been any inappropriate exchanges" between her and the congressman.
Weiner, 46, is married to Huma Abedin, an aide to Secretary of State Hillary Clinton.