Video above: Joran van der Sloot arrives at federal courthouseJoran van der Sloot, the main suspect in the disappearance of Natalee Holloway, pleaded "not guilty" to federal charges Friday.Van der Sloot is charged with one count of extortion and one count of wire fraud against her mother, Bethany Holloway.The arraignment is expected to take place at 11 a.m. at the Hugo L. Black United States Courthouse. Video below: WVTM 13 team coverage ahead of Joran van der Sloot's arraignment The family of Natalee Holloway is expected to be at the court proceeding, including her mother, father and brother. Holloway, of Mountain Brook, Alabama, went on a high school graduation trip to Aruba in 2005. She was 18 years old. She never showed up for the return flight home.Her classmates said they last saw her with Joran van der Sloot, who was 17 at the time, and two others as they left a club.The three said they dropped her off at a hotel. They were questioned and detained but freed because of a lack of evidence.Van der Sloot contacted a cooperating witness via email in 2010. He told them that he would accept $250,000 from Holloway's family in exchange for promising to lead them to her body, identifying the people involved in her death and explaining the circumstances of what happened.He modified his offer so that he would accept the first $25,000 to take the witness to her body, and then on recovery, he would receive the rest of the money. The first $10,000 was given in cash — with another $15,000 wired. This is the basis for the wire fraud charge. Read the full affidavit below. He has not been charged in her disappearance. This is a developing story and will be updated as information becomes available.