Niki D. Williams, 46, pleaded guilty to one count of conspiracy to commit wire fraud and mail fraud and honest services wire fraud and mail fraud.
Williams administered the SAT and ACT exams at a public high school in Houston where she worked.
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In exchange for bribe payments directed to her by co-conspirators William "Rick" Singer and Martin Fox, and in violation of her duty of honest services to the ACT and the College Board, Williams allowed another co-conspirator, Mark Riddell, to secretly take ACT and SAT tests in place of the children of Singer's clients or to replace their exam answers with his own corrected answers. Williams then returned the falsified exams to the ACT and College Board for scoring.
Singer, Riddell and Fox previously pleaded guilty and are cooperating with the government's investigation. Williams is the 41st defendant to plead guilty in this case.
Williams is scheduled to be sentenced on Dec. 21. According to the terms of the plea agreement, the government will recommend one year of supervised release, a fine, forfeiture in the amount of $20,000 and restitution.
WATCH: Latest in arrests of Houston cheating scandal suspects
University of Texas men's tennis coach Michael Center has also been charged in connection with the scandal.
MORE: Actresses, CEOs charged in alleged college admissions scam
Two of the biggest celebrity names on the list are actresses Lori Loughlin and Felicity Huffman. Prosecutors alleged Huffman, Loughlin and 31 other parents from "wealth and privilege" paid a collective $25 million to get their children into colleges.
Prosecutors say this is the largest college admissions cheating scam ever prosecuted in the U.S. Those indicted allegedly paid bribes from $200,000 to up to $6 million each to get their children into the elite schools.
Prosecutors say the alleged scam was run by a college admissions counselor in California named William Singer who used testing centers in Houston and California.
"To facilitate the scam, Singer counseled parents to take their children to a therapist and get a letter saying that because of purported learning disabilities or other issues, the child needed additional time to complete the ACT or the SAT. Once the companies that administered those exams had agreed to the extra time, Singer arranged for the child to take the exam individually with one of the proctors he had bribed either at a location in Houston or at a location in California," said Andrew Lelling, U.S. attorney in Massachusetts.
The federal court documents are 269 pages in all.
No students were charged. In many cases, the students were not aware of the fraud, authorities said.
Head here to read more about the charges against the defendants.
The video in the post is from a previous story.
The Associated Press contributed to this report.