WOBURN - The Somerville man dubbed the "Average Joe" bank robber and his alleged 20-year-old girlfriend accomplice both pled not guilty Thursday to two charges stemming from the Oct. 4 heist of the Sovereign Bank in Winchester.

Arraigned late Thursday afternoon on armed robbery and conspiracy charges, the two Somerville 20-year-olds, Joseph Hart and Jennifer Sheehan, were both ordered into a drug treatment center for 30-days by a Woburn District Court judge.

The pair, appearing together in court yesterday with dark clothing and blankets shielding their faces from public view, is next due in court on Dec. 30 for a pre-trial conference hearing.

Hart and Sheehan were arrested in Charlestown on Wednesday after Hart's own father reportedly tipped-off police to his son's alleged role in the bank robberies. Suspected of holding-up at least eight other banks in the area, Hart may have been involved in as many as dozen heists since last September, police and FBI investigators surmise.

Requesting that Hart be held on $500,000 bail and Sheehan on $15,000, Assistant Middlesex District Attorney Melinda Thompson alleged that the 20-year-old Somerville man had a lengthy criminal history that included several defaults on previous court dates.

Arguing that those missed court appearances offered solid proof that Hart was a flight risk, the prosecutor further insinuated that the 20-year-old was a public danger, as he had been convicted of at least one gun-charge. The Somerville man purportedly alluded to carrying a gun in note passed to the Sovereign Bank teller in Winchester last October.

"The Commonwealth on Mr. Hart is asking for $500,000 bail. Mr. Hart has four defaults on his record, six guilty findings, and [multiple] defaults on his probation. He is a flight risk," the prosecutor said.

"He has hit banks in eight cities and towns and has the same M.O. He hands the teller the note, says he has a gun, and leaves in a nonchalant way. To tie him to these robberies, his own father, as a concerned citizen, stepped up and called the Winchester police," Thompson continued.

Characterizing the prosecutor's $500,000 bail request as "ridiculous," Hart's defense lawyer, attorney William Matthews, claimed that turning his client over to the Middlesex Sheriff's office to be booked and held in a Cambridge detention center would unfairly punish the bank robbery suspect.

The defense attorney further labeled Hart as a victim of a reported heroin addiction, saying the costly habit — which the suspect had attempted to abandon during several failed stints in drug rehabilitation centers — had driven the 20-year-old into a criminal frenzy to avoid withdrawal sickness.

Expressing his certainty that the 20-year-old would be convicted and sent to jail "for a long time" for the charges, Matthews scoffed at Thompson's attempt to link the Somerville man's former weapons-conviction with his purported scribbled notes to bank tellers alluding to a gun.

"I would suggest my client is suffering from a [serious] addiction and that he shouldn't be sent to jail today," Matthews argued, claiming Hart was no different than a rising number of otherwise "good" citizens and youngsters across the Commonwealth suffering from heroin addictions.

"This is a charade in that he's a guy who gets so addicted that he's driven to commit crime," Matthews said.

"The government's case is air-tight. And he will have to go to jail for a long-time unfortunately, but that's a decision for another judge. But these suggestions that he had a gun while dressed in a tee-shirt and a baseball cap...[the gun] would have to be this small," the defense attorney insisted, pinching his fingers together to display a minuscule imaginary weapon.

While Matthews made no quips about the purported mountain of incriminating evidence against Hart, Sheehan's defense, attorney Karen Swenson, insisted that the District Attorney's office had nothing against her client.

Immediately objecting to the judge's decision to arraign Sheehan alongside Hart, Swenson argued that the only evidence investigators had against the 20-year-old woman was the mere fact that she was found with Hart at the time of his arrest.

"There is no evidence against her in this case," Swenson said, appealing to the judge to release the 20-year-old on no bail. "Was she with [Hart] when he was arrested? Yes. Does that mean she was involved in a robbery that took place in October? No. That's why releasing her on personal recognizance is the right thing to do."

To the silent gasped and sobbing denials of three of Sheehan's friends, who sat in the front row of the courtroom, the prosecutor rebutted Swenson's reasoning and claimed that an unnamed source told investigators that the Somerville resident had bragged about the robberies to acquaintances.

However, the defense attorney blasted that statement, telling the judge that a hearsay remark from an anonymous or yet-unnamed source could hardly be considered credible.

Swensen further alluded to police reports from the Winchester robbery where named witnesses at the crime scene recalled seeing a suspect matching Hart's description jumping into a tan car occupied by two other males.

Characterizing those witness statements as far more credible, Swensen questioned what connection authorities had made linking the young woman, who owned and was arrested in a red car, to that original tan-colored suspect vehicle.

"In the police report I've seen, there's a description of somebody getting into a tan car driven by two males. [My client] was stopped in a red car when she was arrested. There's nothing that connects her," Swenson countered, whose arguments were left undisputed and unanswered by the prosecutor.

"She is before this court as a 20-year-old young woman. She's never been arrested before. She is entitled to personal recognizance."

With the two Somerville residents arraigned only for the Oct. 4 Winchester bank robbery, it is widely expected that the pair will be further charged in connection to a number of other heists that occured in Somerville, Cambridge, Arlington, Lincoln, Wakefield, Belmont, Andover, Medford, Danvers, and Littleton.

According to Boston FBI spokeswoman Gail Marcinkiewicz, whether Hart or Sheehan will face additional charges for any alleged involvement in those other bank robberies will be decided in the near future.

"The charging agency would be the U.S. attorney's office, so they would have to make that determination," the spokeswoman commented this morning.

Although clear images of the Somerville man were purportedly captured by video surveillance cameras at several of the targeted banks, members of the FBI Bank Robbery Task Force and local authorities struggled in their attempts to identify the robber because of his plain, everyday features.

Hart's Wednesday arrest came a day after area police gathered in Winchester to strategize on how to identify and capture the elusive suspect, who was dubbed the "Average Joe" bank robber by authorities.

The meeting, which resulted in a media blitz which distributed photos of the suspect across newspaper pages and broadcast airwaves, was widely credited by Winchester Police Lt. James Pierce for leading to the arrests.