NEW YORK (CNN/Money) - ImClone Systems' former CEO Samuel Waksal pleaded guilty to six of 13 charges of securities fraud in an attempt to save family members from facing charges, but that strategy could misfire if prosecutors insist on a presentencing hearing, according to a published report Friday.

Waksal is scheduled to be sentenced Jan. 24, and federal guidelines set a range of seven-to-nine years for the crimes to which he pleaded guilty. But a presentencing hearing could allow prosecutors to present evidence of crimes to which Waksal did not plead guilty, a move that could increase his prison sentence and implicate others in the case, according to the Wall Street Journal.

Prosecutors previously said they were looking for a sentence as long as 10 years.

The government also could compel friends, family members and coworkers to testify in a presentencing hearing; that could include Waksal's daughter and father, who also were caught in the insider trading scandal, the paper reported.

"The Waksal plea is, to say the least, highly unusual," Robert Katzberg, a New York white-collar defense attorney, told the Journal. "It is potentially a very dangerous one."

Indeed, the prosecuting attorney presiding over the case told the federal judge that the government does not consider Waksal's plea to be a "full acceptance of responsibility" and it will seek to introduce additional evidence against him, the paper reported.