It was during a post-divorce, supervised visitation with his daughter that Gerhartsreiter grabbed Reigh and ordered the driver of an SUV to speed off, sending Yaffe, who was trying to rescue Leigh, out of the vehicle, and tumbling to the street.
Gerhartsreiter and Reigh were found six days later in a Baltimore town home that he had purchased a few months earlier.
Defense attorney Jeffrey Denner expressed disappointment that the jury did not buy the insanity defense, but conceded that "it was an uphill battle," especially since there was no record Gerhartsreiter ever sought help for any mental health disorders.
Denner said his client had a "flat" reaction to the verdict and did not say much.
Denner had asked for a sentence of zero to 24 months in prison, citing his client's "diminished" mental capacity. Gerhartsreiter, Denner said, never intended to hurt his daughter.
"You have a guy who loved his daughter too much and made huge mistakes" in showing that love, Denner said.
Denner even told the jury during closing arguments that "this is not a man playing with a whole deck."
The prosecution had dismissed the insanity theory throughout the trial and referred to Gerhartsreiter by his real name. During his closing arguments, Assistant District Attorney David Deakin implored the jury not to buy into it.
"Don't let him get away with that," Deakin said, "Don't let this insanity defense be the culminating manipulation in a lifetime of lies designed to try and get what he wanted."
Despite the two convictions, the jury found Gerhartsreiter not guilty of giving law enforcement a false name and not guilty of a second assault charge that included battery.
Though he entered the courtroom with a smirk on his face, he showed little emotion during the reading of the verdict and once mouthed "Oh s***" after the second guilty verdict.
Yafee was seen smiling as the verdict was read.
Because Gerhartsreiter is still an illegal immigrant, having come to the U.S. from Bavaria on a student visa, he will face federal deportation proceedings after he serves out his sentence, Suffolk County District Attorney Dan Conley told ABC News.
Bizarre details of Gerhartsreiter's three decades of deception came fast and furious during the trial, with witnesses recounting a litany of fantastic tales that were alternately flamboyant or strange, or both.
Gerhartsreiter, who had claimed that his daughter Reigh communicated with him telepathically the day she was kidnapped, had a history of passing himself off ot only as a Rockefeller, but as a rocket scientist and a cardiovascular surgeon, among other professions.
As this case winds down, another may be heating up. Conley told ABC News that a federal grand jury is convening in California in the 1985 disappearance of a newlywed couple. Gerhartsreiter, who was using yet another name at the time, was living in the couple's guest house, has been eyed by authorities in the case, but not charged.
The Associated Press contributed to this report.