BOSTON -- The man who calls himself Clark Rockefeller was not insane when he snatched his young daughter during a supervised visit in Boston last year, a Suffolk County jury said on Friday.

After more than four days of deliberations, the jury of eight women and four men found Rockefeller, 48, who is really Christian Karl Gerhartsreiter, guilty of two felony charges: a custodial kidnapping charge that carries a five-year prison sentence, and an assault and battery with a dangerous weapon charge that carries a 10-year sentence. Gerhartsreiter was found not guilty of the two lesser charges of assault and battery and providing a false name to authorities.

Gerhartsreiter used the name of the wealthy oil tycoon for years before he kidnapped his then-7-year-old daughter, Reigh Boss, in July 2008. A social worker supervising the visit was injured as Gerhartsreiter fled the scene.

Prosecutors convinced the jury that Gerhartsreiter went to great lengths to plan the abduction. Defense attorneys unsuccessfully argued that Gerhartsreiter was insane at the time and had no way of knowing right from wrong or understanding the criminal nature of his actions.

Calling it a "fair and just verdict," Suffolk County District Attorney Daniel Conley thanked his prosecution team and said he was happy to bring justice to Gerhartsreiter's ex-wife, Sandra Boss, and the couple's daughter, Reigh.

"Their personal lives were thrust into the national and international spotlight, and we are very pleased they got some sense of justice today," Conley said.

The jury foreman offered a brief statement on behalf of the entire jury after the verdict.

"We were very thorough in our deliberations. We methodically examined every piece of evidence. We considered every element of every charge and every defense," foreman Michael Gregory, a law professor a Harvard University Law School, said, adding that the jury was "confident that our verdict is fair and just and based only on the information that we were legally allowed to consider."

Gerhartsreiter will be sentenced at 2 p.m. Friday.

The jury was handed the case Monday afternoon, but during deliberations, they returned to the courtroom twice with questions for the judge.

On Wednesday, jurors asked Suffolk County Superior Court Judge Frank Gaziano about the criteria for criminal responsibility. Gaziano said that the state needed to prove the defendant understood the legality of his actions and knew that what he was doing was morally wrong.

The jury on Tuesday asked to listen to a 14-minute interview the FBI conducted a few hours after his arrest in Baltimore. On the tape, Gerhartsreiter is heard repeatedly saying that all he wants to do is be a father and that he wants to wake up to her every day.

Assistant District Attorney David Deakin said Gerhartsreiter led a "lifetime of lies" that started when he moved to the United States from Germany when he was 17.

"This is not a case about madness. It's a case about manipulation," Deakin said.

Deakin laid out five different aliases for the jury that Gerhartsreiter allegedly used for years, which included the Rockefeller name that he was using when he met Boss. She testified during the trial that she believed his stories and he was "not the person he said he was."

While Gerhartsreiter may be "troubled," Deakin said there is no doubt he knew it would be wrong to kidnap his daughter. Deakin portrayed Gerhartsreiter as a controlling man who did not want to lose the lifestyle he was accustomed to with his wealthy wife.

"Don't let his insanity defense be the culminating manipulation in a lifetime of lies designed to try to get what he wants," Deakin said during his closing statement.

During defense attorney Jeffrey Denner's closing statements, he said his client led a life of delusion and was pushed to the breaking point when Boss filed for divorce and he later lost custody of his daughter, calling it the "perfect storm that sent him over the edge."

Denner said that Gerhartsreiter believed that his daughter was communicating with him telepathically, and that "he believes that she is in great danger and he has to rescue her."