NEWARK, New Jersey (Reuters) - A former federal prosecutor went on trial for murder on Monday, defending himself before anonymous jurors and threatened with an electric shock if he steps near them.

In an unusual move typically reserved for trials of gang members and mobsters, the nameless jury was created last week for the trial of Paul Bergrin, 55, a prosecutor who became a prominent defense attorney and was charged with orchestrating the 2004 murder of a confidential witness in a federal drug case against one of his clients.

During pretrial proceedings, prosecutors argued that safety and privacy concerns demanded that potential jurors remain anonymous. At a hearing on August 30, U.S. District Judge William Martini agreed to withhold jurors' names and the names of their employers, although he did not say how long the information would remain confidential.

In an typical criminal trial, attorneys learn the names, addresses, workplaces and other personal information about the prospective jurors from whom they select their jury.

But there's nothing typical about the trial that opened on Monday in Newark federal court, where the lawyers will know nothing about the jurors other than their hometowns and a few other small details gleaned from their answers to an extensive questionnaire.

In New Jersey federal courts, which includes courthouses in Newark, Trenton and Camden, anonymous juries are created about six times per year on average, said Bill Holland, director of court services for the U.S. District Court for the District of New Jersey.

Bergrin, who is representing himself with assistance from a court-appointed attorney, Lawrence Lustberg, has already been severely restricted in his physical movements around the courtroom. He has been ordered to remain within a zone that measures just a few square feet and keeps him away from the jury and the witness box. If he steps outside the proscribed zone, the judge has warned, he will be ordered to wear an electric shock monitoring ankle bracelet that will enforce those restrictions.

Bergrin is accused of arranging the 2004 shooting in broad daylight on a Newark street of a crack cocaine buyer named Kemo McCray, a witness who was to testify against one of Bergrin's clients, a drug kingpin.

The murder charges against Bergrin, are part of a larger 33-count indictment filled with racketeering and other allegations that government officials have said make Bergrin "no different than a street gangster," according to a press release the U.S. Attorney's Office in the District of New Jersey issued after his indictment in May 2009. Martini decided to try the murder counts separately to avoid the risk of prejudice.

If convicted, Bergrin faces up to life in prison.

Bergrin's co-defendants, including another New Jersey lawyer, Thomas Moran, have already pleaded guilty.

(Reporting by Jennifer Golson; Editing by Barbara Goldberg and Greg McCune)