Garrett said that from van der Sloot's demeanor on the interrogation tapes, he appears to be trying to smooth talk investigators.
"He thinks he can talk his way out of just about anything," he said.
Ricardo Flores, who told ABC News that he considered his only daughter to be his "co-pilot" in life, said he has struggled to make any sense of her death.
" The spirit and soul of my daughter is with still us," he said. "I have four sons in body and a daughter in soul and spirit."
As van der Sloot faces murder charges in Peru, he's also being investigated in the United States.
U.S. authorities told ABCNews.com that they launched an extortion investigation of van der Sloot six weeks ago, but they did not issue a warrant for his arrest until this week because they lacked sufficient evidence.
The federal extortion investigation began in late April, a spokeswoman for the U.S. Attorney's office in Birmingham said.
On May 10, $15,000 was wired to a Netherlands bank by someone in Mountain Brook, Ala., allegedly in exchange for a promise by van der Sloot to provide information about what happened to Holloway and the whereabouts of her remains.
Van der Sloot had for five years been the prime suspect in the disappearance on Holloway, a high school student from Mountain Brook who vanished in Aruba on May 30, 2005.
Van der Sloot, a Dutch national who lives in Aruba, was arrested Thursday in Chile and was extradited today to Peru to face murder charges in Flores' death. He told authorities he met Flores, but denied killing her.
For several weeks van der Sloot had been on the radar of American officials who, in a criminal complaint released Thursday, said he planned to extort $250,000 from the unidentified victim.
A criminal complaint alleging the extortion was filed Thursday, just days after Flores was found dead and van der Sloot had fled to Chile.
Authorities said their charges were not the result of the Peru death.
"This was completely separate and before the girl was killed in Peru," said Peggy Sanford, spokeswoman for the U.S. Attorney's Office in Birmingham. "This investigation had been going on. It was a complete coincidence and tragedy that the other woman was murdered."
The complaint does not name the person whom van der Sloot was trying to extort, by providing information about Holloway's death, but Sanford suggested, van der Sloot had initiated contact by approaching the alleged victim.
"He extorted, or attempted to extort someone, an individual, in exchange for the location of Natalee Holloway's remains and information about her death. Mr. van der Sloot made efforts to extort someone and get money," said Sanford.
U.S. law enforcement, however, may never get to try van der Sloot for the alleged extortion scam. He arrived in Peru today under armed guard.
Famed criminal defense lawyer Roy Black told ABC's "Good Morning America" that, "The murder case in Peru takes precedence over" the extortion charges, and that the chances of van der Sloot getting extradited to Alabama "are zero."
"He's going to get a very long sentence in Peru," Black said. "By the time he gets out of jail, if he ever does, this would be a footnote in history."
The lawyer said, however, that the Holloway disappearance could be used "as evidence of proof in Peru," and the Holloway family may ask a Peru court "for a longer sentence because of Natalee's murder."