What to know about the whistle-blowers who accused Ken Paxton of wrongdoing.

The four men behind the whistle-blower lawsuit that landed the Texas attorney general, Ken Paxton, in political peril were once employees and allies whom Mr. Paxton handpicked to advance his conservative agenda.

The four staff members — James Blake Brickman, David Maxwell, Mark Penley and Ryan Vassar — joined forces when they decided that the actions they saw involving Mr. Paxton were too troubling to let stand.

They filed the whistle-blower lawsuit in 2020 after Mr. Paxton ignored their repeated expressions of concern. According to the 372-page filing that laid out their allegations, the four staff members fell out with Mr. Paxton after the F.B.I. in 2019 raided the home of Nate Paul, a wealthy real estate investor in Austin and a donor to Mr. Paxton. Convinced that the authorities had acted unlawfully, Mr. Paul enlisted Mr. Paxton’s assistance.

In the lawsuit, the four men allege that Mr. Paxton not only used his influence to set up and attend a meeting for Mr. Paul and his lawyer with the staff of the local district attorney’s office, but had also assigned a private attorney to look into Mr. Paul’s concerns.

The four said in the complaint that they believed Mr. Paxton “had violated Texas criminal law, including but not limited to the laws regarding bribery, improper influence, and abuse of office.”

Mr. Paxton, they said in legal documents, “has flagrantly violated and apparently believes he is above the very law he promotes on his own website.”

Mr. Paxton responded by suspending and later firing them.

Earlier this year, Mr. Paxton said he had reached a settlement with them. But more trouble followed when he asked the state to pay them $3.3 million in compensation, leading a Texas House committee investigating his actions to schedule a vote Saturday afternoon on whether to impeach Mr. Paxton.

During a news conference on Friday, Mr. Paxton called the efforts to impeach him “illegal” and “political theater,” and he added that he was not provided with an opportunity to challenge allegations made against him.

He also said he was confident the calls for his impeachment will not prevail. “I hope the House makes the right decision, but if not, I look forward to a quick resolution in the Texas Senate,” he said.

These are the four whistle blowers.

James Blake Brickman

Mr. Brickman was deputy attorney general for policy and strategy initiatives from February 2020 until his termination in Oct. 20, 2020, according to the legal filings. The filings said that Mr. Brickman and Mr. Paxton had a good working relationship before the scandals surfaced and that at Mr. Paxton’s request, Mr. Brickman moved with his wife and three children to Austin to work with him. The filings allege that months before Mr. Brickman began expressing concern about Mr. Paxton’s behavior, the attorney general regularly lauded his work, once calling him an “amazing addition,” to his office.

But after the staff members questioned the efforts to assist Mr. Paul, the relationship soured, the filings say. Mr. Brickman was asked to step away from key meetings, a move that he said in court documents was intended to “diminish Brickman’s duties and responsibilities to punish him, to try to intimidate and embarrass or humiliate him.”

Before coming to work for Mr. Paxton, Mr. Brickman was the chief of staff for former Gov. Matt Bevin of Kentucky, a Republican. He has also served as chief of staff for former Senator Jim Bunning of Kentucky, also a Republican.

David Maxwell

For 10 years Mr. Maxwell oversaw a team of about 350 employees with the Texas attorney general’s office, where he worked as the deputy director and director of the law enforcement division. The lawsuit alleges that Mr. Maxwell came into conflict with Mr. Paxton when he learned of Mr. Paxton’s attempt to insert himself in the federal inquiry connected to Mr. Paul. In the lawsuit he filed with fellow whistle-blowers, Mr. Maxwell and Mark Penley asserted that “many of Paul’s complaints were outside state jurisdiction.”

In legal filings, Mr. Maxwell described himself as an “honest, thorough and tough law enforcement investigator.” His career in law enforcement spanned about 50 years, including 35 of them with the Texas Department of Public Safety, most of that time as a Texas Ranger, according to legal documents.

Mr. Maxwell is also known in Texas for helping to identify the man who raped and fatally stabbed his sister, Diane Maxwell Jackson, decades after the crime, which took place in 1969. A judge sentenced her killer to life in prison in 2004.

Mark Penley

Mr. Penley worked as the deputy attorney general for criminal justice under Mr. Paxton for just over a year, from Oct. 8, 2019 until Nov. 2, 2020. During that time, he supervised a team of about 220 employees in various divisions, including criminal prosecutions, special prosecutions, criminal appeals and crime victims services, according to legal filings. Mr. Penley, a retired federal prosecutor, has spent nearly 40 years practicing law.

Mr. Penley also found himself at odds with Mr. Paxton several times as Mr. Paxton worked to help Mr. Paul navigate his legal problems. According to the lawsuit, Mr. Penley at one point refused to sign a memo approving the hiring of the special prosecutor assigned to the raid at Mr. Paul’s properties.

Ryan Vassar

Until late 2020, Mr. Vassar served as a deputy attorney general for legal counsel for the attorney general’s office. He was the last of four former staff members from Mr. Paxton’s office to be ousted after the accusations of corruption surfaced against Mr. Paxton. Mr. Vassar said in the lawsuit that he refused many requests from his former boss to help unearth information that would help Mr. Paul.

Mr. Vassar had a long legal career in Texas before the scandal broke. Most recently, he has taken a job as a general counsel with the Cicero Institute, a nonprofit public policy organization, according to the institute’s website. For three years, Mr. Vassar worked as a legal clerk for Justice Don R. Willett of the Supreme Court of Texas. He graduated with an accounting degree from Texas Tech University and a law degree from South Texas College of Law Houston.