Author Derek Armstrong said he had Peterson take a lie detector test as a condition of writing a book about the case, and Armstrong said on questions about Kathleen Savio's murder, Peterson showed no deception.
"I'm not experienced with polygraphs at all," Peterson told Dateline NBC's Hoda Kotb. "I was answering truthfully."
But how truthful was the polygraph? Peterson's attorney Joel Brodsky decided which topics could be addressed during the examination and which could not be discussed, Armstrong said.
One topic in particular was forefront in Armstrong's mind, but Brodsky wouldn't allow it.
"The key one would be did he hire someone or know of someone being hired to harm either Kathleen Savio or Stacy Peterson," Armstrong said of the polygraph test. "I wasn't allowed to ask that question."
Attorney Joel Brodsky said he did not put limits on the test. Brodsky has referenced that particular polygraph in a number of recent interviews including one during NBC's Today Show on Friday morning. On the night of Peterson's arrest, Brodsky told NBC Chicago, "If you recall, Drew Peterson already took a polygraph exam regarding Kathleen Savio's death for that book, 'Drew Peterson Exposed' and passed the polygraph exam totally."
The polygraph Peterson submitted to also contained a section of six questions about the disappearance of his fourth wife, Stacy Peterson. Of the six questions, Armstrong said Peterson was found to be not deceptive in answering three of the questions, including whether he harmed Stacy during the time of her disappearance.
However, Peterson was found to be deceptive in three of his answers in the section about Stacy Peterson, according to Anderson.
Peterson discussed these answers with NBC's Hoda Kotb:
Tune in for a special Dateline NBC tonight for to see Hoda Kotb's full interview with Drew Peterson. The two-hour Dateline, which will feature one hour of coverage focusing on Drew Peterson's arrest, begins tonight at 8 p.m.