Inquiry Seeks Twitter User in Brooklyn Bridge Flag Case

The Twitter account purportedly representing an 'all-powerful' coalition of radical cyclists has claimed responsibility for knocking out Metro-North Railroad service, swinging the World Series and strong-arming Bruce Springsteen into changing a song title to 'Thunder Lane.'

So when the account, @BicycleLobby, wrote on Twitter last month that it had placed white flags atop the Brooklyn Bridge 'to signal our complete surrender' of its bicycle path to pedestrians, most followers of the self-described 'parody account' allowed themselves a chuckle at the several news organizations that reported the remark as a proper confession before backtracking.

On Friday, though, with the authorities still searching for the perpetrators in the flag affair, it seemed that @BicycleLobby had not been cleared. Steve Vaccaro, a lawyer for the account's author, who has remained anonymous, said Twitter had received a subpoena from the Manhattan district attorney's office in a bid to identify his client.

'He's claimed credit for the moon landing, for the faking of President Obama's birth certificate, for the crash of the New York Times website,' Mr. Vaccaro said. 'It should be transparently clear to anyone that this was a joke.'

The district attorney's office declined to comment.

Meanwhile, the New York Police Department suggested on Friday that it had made some progress in the investigation. A department spokesman said 'we have an idea' of who was responsible for replacing the American flags with the white flags on July 22, but added that it was unclear when any arrests might be made.

The role of social media posts in court has received increased attention in recent years, perhaps most notably in a case involving an Occupy Wall Street protester, with Twitter at times resisting requests for information about its users.

Twitter declined to discuss the flag case, but said in a statement that as a policy, it notified users of requests for their information 'prior to disclosure unless we are prohibited from doing so.'

Word of the subpoena rankled cycling and pedestrian advocates on Friday, particularly as cycling groups have pressed the Manhattan district attorney, Cyrus R. Vance Jr., to prosecute driving offenses more aggressively.

In a series of posts on Friday, @BicycleLobby had another concern: making clear that, for at least one day, it was not kidding.

'These last tweets are 100% true,' it wrote. 'Everything else posted before today is clearly a joke.'