A lawyer for a German man who pretended to be a member of the storied Rockefeller family argued Friday that his client's conviction for kidnapping his daughter should be thrown out because his trial was marred by the "evisceration" of his insanity defense.

Christian Karl Gerhartsreiter, who used the name Clark Rockefeller as one of his aliases after moving to the United States in the 1970s, was convicted in 2009 of kidnapping his 7-year-old daughter during a supervised visit after he and his wife divorced. He also was convicted of assault and battery with a dangerous weapon for instructing his hired driver to speed away after he snatched his daughter, injuring a social worker supervising the visit.

During closing arguments at his trial, the prosecutor noted the defendant's history of using aliases and urged jurors not to let his insanity claim be "the culminating manipulation in a lifetime of lies."

The statement denigrated the insanity claim as an illegitimate defense, Gerhartsreiter's lawyer, Jeffrey Denner, argued before the Massachusetts Appeals Court on Friday. He also argued that the state's expert witness was not qualified to testify because he was unaware of elements of insanity defense law in Massachusetts.

"I think some lines were crossed here," Denner said.

Assistant District Attorney Jack Zanini argued that the prosecutor was not disparaging the insanity defense itself, but instead was highlighting evidence during the trial about the numerous false stories Gerhartsreiter told about his past.

"You can call someone a liar, if in fact they are a liar," he said. "He didn't belittle or criticize the use of psychological testimony."

The three-judge panel did not indicate when it would rule on the appeal.

During the trial, several witnesses testified about elaborate tales Gerhartsreiter told, including his claims of being a physicist, ship's captain and debt negotiator for small countries. Prosecutors said he used the stories and various aliases to ingratiate himself in wealthy circles in New York, Boston and Los Angeles.

Two mental health experts testifying for the defense said Gerhartsreiter was delusional and legally insane when he kidnapped his daughter.

The state's expert said Gerhartsreiter was not insane and knew his conduct was wrong.

Gerhartsreiter and his daughter were found in Baltimore six days after the kidnapping in August 2008. The girl was unhurt.

After he was apprehended, authorities in California named him a "person of interest" in the 1985 unsolved disappearance and presumed killings of a San Marino, Calif., couple, Linda and John Sohus.

In January, a judge in Alhambra, Calif., found there is enough evidence to try Gerhartsreiter in the killing of John Sohus, the son of a woman who rented her guest house to Gerhartsreiter.

Forensic testing on bones dug up in the yard of the Sohus property in 1994 suggested they belonged to John Sohus. No sign of Linda Sohus has ever been found.

Gerhartsreiter is being held on $10 million bond in that case as he awaits a trial in January.

He has nearly completed the four- to five-year sentence he received in the Massachusetts kidnapping case.