Bud Selig is expected to announce next week that he is beginning a formal investigation into Barry Bonds' steroid use, opening the door to possible sanctions against the embattled slugger. The Daily News reported yesterday that the commissioner had decided on his course of action and would likely announce an investigation in the near future, although Selig still has not decided on the details. Selig did not return calls for comment yesterday, but sources said he was still deliberating on whether to appoint an outside investigator or have Major League Baseball officials run the probe. "The point is, he's going to look into it," a high-ranking MLB official said.