Joran van der Sloot, the main suspect in the 2005 disappearance of Natalee Holloway, pleaded guilty Wednesday to federal extortion charges related to the Alabama teenager's disappearance and was sentenced to 20 years in prison.

As a part of the plea deal, van der Sloot agreed to provide information about the 18-year-old's disappearance in Aruba to Holloway's mother, Beth Holloway.

Van der Sloot said he killed Natalee Holloway on a beach, bludgeoned her face with a cinderblock and then disposed of her body in the ocean, according to a partial transcript of a proffer meeting he had with prosecutors on Oct. 3.

Van der Sloot said Natalee Holloway had wanted to go back to her hotel that night, but he arranged for the two to get dropped off "a little bit further away from her hotel so we could walk back … and I might still get a chance to be with her," van der Sloot said in the meeting with prosecutors.

As the two walked alone on the beach, van der Sloot said he "laid her down" and they began kissing, and then Holloway told him to stop.

But he said he kept pursuing her, and Natalee Holloway "knees me in the crotch," van der Sloot said, according to the transcript.

"When she knees me in the crotch I get up on the beach and I kick her extremely hard in the face," he continued.

He said the teen was then "laying down unconscious, possibly even dead," according to the transcript.

Van der Sloot told prosecutors he then found a cinderblock on the beach and "smashed" her head with it.

He said he walked into the ocean up to his knees and pushed Natalee Holloway's body into the water.

In court Wednesday, as van der Sloot pleaded guilty to federal extortion charges, Beth Holloway said, "Joran, for 18 years you denied killing my daughter," and now "you have finally admitted that you, in fact, have murdered her."

"You are a killer. I want you to remember that every time that jail door slams," she said.

"Even if you have finally confessed ... you can't be tried here for her murder. But I do employ the court to give you the maximum sentence possible," Beth Holloway said.

Turning to van der Sloot, she added, "By the way, you look like hell, Joran. I don't know how you are going to make it."

She left the podium in tears.

Van der Sloot, 36, apologized in court to the Holloway family and his own family, and said he hopes "the statement that I provided will provide some kind of closure."

"I am not the same kind of person today as I was then, I have given my heart to Jesus Christ," he said.

Natalee Holloway's dad, Dave Holloway, said in a statement, "Today's proceeding confirmed that this defendant murdered Natalee and then tortured and extorted those who loved her most."

"He is evil personified," Dave Holloway said.

The judge Wednesday accepted the plea agreement and said van der Sloot brutally murdered two young women who refused his sexual advances, but that his confession in the Natalee Holloway case cannot be used against him.

The judge sentenced van der Sloot to 20 years in prison to run concurrently with the Peruvian sentence. He will also have to pay restitution to Beth Holloway.

Van der Sloot initially 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.

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 Beth Holloway through her lawyer, John Q. Kelly, 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, 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.

After court ended Wednesday, Beth Holloway told reporters, "I got the answer I’ve been searching for for the last 18 years. ... For me, reaching the end of the nightmare is better than closure."