SACRAMENTO (Reuters) - California Attorney General Bill Lockyer said on Wednesday he would return a $50,000 campaign contribution from Oracle Corp. to prevent the appearance of conflict of interest as he probes a controversial contract the state signed with the software giant. "Full, fair, nonpartisan and nonpolitical investigations have always been the standard for this office," Lockyer said in a statement. "Returning the campaign contributions from Oracle will help ensure that partisans don't undermine public confidence" in the Oracle probe, he said. Lockyer, a Democrat, has come under attack from some Republicans for the $50,000 donation, which he said was...