Updated

Defense lawyers continued to question a witness Friday who said Lisa Montgomery was not insane when she killed an expectant mother and cut her baby from her womb in 2004.

Dr. Park Dietz, a rebuttal witness for the prosecution, was mostly asked Friday morning about Internet searches Montgomery made for such pregnancy topics as home births, Caesarean sections and drugs used to induce labor.

Montgomery, 39, is accused of strangling Bobbie Jo Stinnett, 23, in the victim's Skidmore home and then cutting the baby from her womb. Montgomery's attorneys claim she was mentally ill and didn't understand the consequences when she killed Stinnett on Dec. 16, 2004.

Dietz has suggested that rather than suffering from pseudocyesis, which causes a woman to falsely believe she is pregnant and exhibit outward signs of pregnancy, Montgomery claimed to be pregnant because she wanted attention.

Dietz said the Internet searches provide little proof of whether she was planning a crime or sincerely believed she was pregnant. He said other evidence was much more compelling.

"I believe the confession is proof positive that my theory is the correct one," said Dietz, who has worked on other high-profile cases, including those of child killers Andrea Yates and Susan Smith, serial killer Jeffrey Dahmer and Unabomber Ted Kaczynski.

Montgomery's attorneys argue that threats to Montgomery's delusion about being pregnant caused her to enter a dreamlike, dissociative state when she drove to northwest Missouri and killed Stinnett.

Montgomery was arrested the next day in her Melvern, Kan., home after spending the morning showing off the baby. She has pleaded not guilty to a federal charge of kidnapping resulting in death.

Prosecutors say Montgomery is faking mental illness to escape a possible death sentence, which they plan to pursue if she is found guilty.

Dietz agreed, noting that Montgomery had a history of lying and had offered several accounts of the killing.

Shortly after her arrest, Montgomery claimed she acted alone. But this spring she began telling authorities that her brother, Tommy Lee Kleiner, was with her at the time of Stinnett's murder.

Both sides have said it was impossible for Kleiner to have been with Montgomery because he was meeting with a parole officer in Osage County, Kan., at the time of the killing. After Kleiner's alibi became known, Dietz said, Montgomery gave a prison psychiatrist an account of the killing that didn't include Kleiner.

Dietz said if Montgomery believed she was pregnant, she would have a consistent story.

Dietz also said Montgomery told her husband, Kevin, that she was scheduled to deliver on a different day than she told her friends.

He noted that during one other faked pregnancy, Montgomery had reported she was pregnant with twins. He suggested her motive for faking pregnancy might have been to put the spotlight on herself.

"A woman who claims she is pregnant with twins gets even more oohs and ahs and attention," he said.

He also mentioned several efforts by Montgomery to falsify evidence to support the pregnancy claim, including doctoring an ultrasound photo.

"The ultrasound is one of the biggest smoking guns to prove the defendant knew she wasn't pregnant in 2004," Dietz said. "It would not need to be done by someone who believed she was pregnant."

During cross-examination Thursday, the defense asked Dietz about his testimony in the case of Yates, a Texas mother who drowned her children.

Her 2002 conviction was overturned after Dietz testified that before the drownings, NBC ran a "Law & Order" episode about a woman who was acquitted by reason of insanity after drowning her children. Later, it was learned that no such episode existed.

Dietz said he had been confused.

A subsequent jury found Yates not guilty by reason of insanity.