Jodi Arias claims she killed her ex-boyfriend Travis Alexander in self-defense, even though she had given authorities other stories about how he died in the past.

She said during direct examination this week that she can’t remember much about the day Alexander died, including the moments where he was stabbed 29 times.

On Thursday though, prosecutor Juan Martinez began questioning Arias’ claims that she couldn’t remember the specifics about the brutal slaying.

One part of the exchange played out, “Do you have problems with your memory, Ma’am?” Martinez asked.

“Sometimes,” Arias quickly answered.

Thursday night, HLN’s Dr. Drew talked to body language expert Janine Driver who focused on Arias’ head nods during the first day of cross-examination.

“It's interesting she deviates from her baseline,” Driver explained. “We call this ‘norming’ -- what is someone's normal behavior. While she says ‘no’, Dr. Drew, you may have noticed she subtly nods her head ‘yes’.”

She added, “We saw this with Bill Clinton when he said, ‘I did not have sexual relations with that woman’. She's saying ‘no’, but her non-verbal is saying ‘yes’."

The trial resumes Monday on truTV's In Session and HLN.

Dr. Drew On Call airs Monday through Wednesday on HLN at 9 p.m. ET.  Follow the show on Facebook and Twitter @DrDrewHLN.

RELATED LINKS:
-Photos: Jodi Arias giggles during harsh cross exam
-Showdown on the stand: Arias vs. Martinez
-Jodi Arias trial: 133 evidence photos