France ? Investigating judges filed preliminary charges Monday against a trader accused of causing billions of dollars in losses for France’s second-largest bank. He was released from custody while the thorny investigation continues.

Preliminary charges of “breach of trust” and unauthorized computer activity were filed against Jerome Kerviel, his lawyer, Christian Charriere-Bournazel, told reporters.

The judges did not pursue a fraud charge sought by the prosecutor’s office or even continue to hold him as the prosecutor wanted for fear he might flee. It was not immediately clear whether the judges were pursuing charges of forgery, also requested by the prosecutor.

The charges came as Paris prosecutor Jean-Claude Marin gave a glimpse for the first time of what motivated the 31-year-old futures trader: not tremendous greed but simply the adrenaline rush of trading, and perhaps the promise of a better-than-average bonus.

The bank and prosecutors have said Kerviel did not appear to have profited from his unauthorized dealings, and his lawyers described him as a “modest boy” who got in over his head.