Joran van der Sloot, the main suspect in the unsolved 2005 disappearance of Natalee Holloway, is expected to plead guilty on Wednesday to federal extortion and wire fraud charges in Alabama.

Van der Sloot pleaded not guilty to the extortion and wire fraud charges in June after he was extradited to the U.S. from Peru, where he had been serving a 28-year sentence for the 2010 murder of 21-year-old Stephany Flores.

Suspicion still surrounds van der Sloot in connection to 18-year-old Holloway's May 2005 disappearance in Aruba.

Holloway was last seen with a group of young men, including van der Sloot, then 17. Van der Sloot was detained as a suspect in Holloway's disappearance and later released.

In 2010, van der Sloot was indicted by a federal grand jury for allegedly trying to extort Holloway's family.

Federal prosecutors alleged that in March 2010 van der Sloot contacted Holloway's mom, Beth Holloway, through her lawyer, and claimed he would reveal the location of the teen's body in exchange for $250,000, with $25,000 paid upfront. During a recorded sting operation, Beth Holloway's attorney, John Q. Kelly, met with van der Sloot at an Aruba hotel, giving him $10,000 in cash as Beth Holloway wired $15,000 to van der Sloot's bank account, according to prosecutors.

Then, van der Sloot allegedly changed his story about the night he was with Natalee Holloway, prosecutors said. Van der Sloot claimed he had picked Natalee Holloway up, but she demanded to be put down, so he threw her to the ground. Van der Sloot said her head hit a rock and he claimed she died instantly from the impact, according to prosecutors.

Van der Sloot then took Kelly to a house and claimed that his father, who had since died, buried Natalee Holloway in the building's foundation, prosecutors said.

Kelly later emailed van der Sloot, saying the information he had provided was "worthless," according to prosecutors. Within days, van der Sloot left Aruba for Peru.