Mark Zaid is one of the attorneys representing the whistleblower who filed the formal complaint against President Trump, which ultimately led to the opening of impeachment hearings and a Senate trial against the president.

The whistleblower came forward with allegations that the president had asked the leader of Ukraine to investigate former vice president Joe Biden and his son, Hunter. The White House later released a memo from the call, which took place in July 2019, and the complaint was declassified.

Zaid and co-counsel Andrew P. Bakaj, who is himself a former CIA officer, expressed concern over their client’s personal safety. In a letter to acting Director of National Intelligence Joseph Maguire, they said that there was a $50,000 “bounty” for information on their client’s identity and cited concerns about President Trump’s public comments about the whistleblower.

Zaid and Bajak stated that their client was entitled to anonymity based on federal law. In a statement released on September 30, 2019, which can be read here, Zaid explained a whistleblower does not have to have first-hand knowledge of an incident in order to be credible.

“In my more than twenty years of representing national security whistleblowers, and fifteen years since the Office of the Director of National Intelligence was created, I have never known nor observed a policy that a whistleblower must have first-hand information to file a complaint. My experiences have always been that whistleblower must provide evidence that can be substantiated, whether through documents or identification of witnesses. No whistleblower law I know of has any personal knowledge requirement.”

Here’s what you need to know about Mark Zaid.

1. Mark Zaid Has Previously Represented Clients In a Civil Lawsuit Against Donald Trump

Mark Zaid was part of a legal team that filed a civil lawsuit against President Donald Trump and the Trump business in March of 2017. Zaid represented Diane Gross and Khalid Pitts, the married owners of the Cork Wine Bar in Washington, D.C.

The couple opened their restaurant in 2008. They claimed that their business suffered after the Trump International Hotel opened nearby. Gross and Pitts claimed in the lawsuit, which was filed in the District of Columbia Superior Court, that the competition from the Trump Hotel was unfair to them and other restaurants in the area because the hotel may attract customers looking for favor with the president.

The couple suggested that the president either divest from the business or that the hotel cease operations. The Trump Organization referred to the lawsuit as a “wild publicity stunt.”

In November of 2017, a federal judge dismissed the case. District Judge Richard J. Leon wrote in his opinion that a person’s fame does not equal an unfair competitive advantage. Judge Leon explained that siding with the Cork Wine Bar would have had far-reaching implications, according to the Washington Post. “I would be foreclosing all manner of prominent people — from pop singers to celebrity chefs to professional athletes — from taking equity in the companies they promote.”

Zaid told Reuters after the judge issued the decision, “We are disappointed that Judge Leon viewed a President profiting off of his public office as legitimate business conduct.”

2. Mark Zaid’s Clients Have Included FBI Whistleblower Sibel Edmonds

Mark Zaid has previous experience defending government whistleblowers. His past clients have included Sibel Edmonds, a former FBI translator. She was hired in September of 2001 to work on counter-terrorism and counterintelligence investigations.

Edmonds was fired in March of 2002 after raising suspicions that one of her fellow translators had engaged in espionage. As explained in the lawsuit, Edmonds accused her co-worker of having previously been “employed by an organization that was a target of an ongoing FBI investigation; had ongoing contacts with investigation targets; leaked information to such targets; translated wiretaps concerning these targets; and told others not to translate such wiretaps.”

The Justice Department’s inspector general determined in 2005 that the FBI had not adequately investigated Edmonds’ claims and that the agency should have taken her more seriously. Edmonds told the New York Times at the time that she felt “vindicated” by the Inspector General.

Edmonds sued the U.S. government, arguing that her firing had been unjust. But a federal appeals court dismissed the case in May of 2005. The judges ruled that the case could expose critical national security issues. The American Civil Liberties Union urged the Supreme Court to look into the case, but the high court declined to hear the case.

3. Zaid Represented the Father of Dodi Al Fayed, Who Had Been Dating Princess Diana, In a Case Against the CIA

Mark Zaid is currently defending a CIA whistleblower but he also has prior experience going against the CIA. In 2000, Zaid represented Mohamed Al Fayed, who owned the Harrods Department Store in London, England at the time. His son, Dodi Al Fayed, had been dating Princess Diana in 1997. He died alongside her on August 31, 1997, in the car crash in France.

Al Fayed alleged that the CIA and the NSA may have information related to the deaths of Princess Diana and his son. Al Fayed claimed that people who did not approve of his son’s relationship with Diana may have conspired to kill them and that U.S. officials may have knowledge pertaining to this allegation.

20 years ago today we lost #PrincessDiana. I remember that day vividly. Do you? I became #AlFayed's attny handling case 2000 – 2003 pic.twitter.com/aK0PiCOXIA — Mark S. Zaid (@MarkSZaidEsq) August 31, 2017

Zaid represented Al Fayed in a Freedom of Information lawsuit filed against the CIA. The lawsuit included an allegation that the National Security Agency “may have secretly recorded Princess Diana’s telephone conversations.” The U.S. Court of Appeals for the D.C. Circuit ruled against Al Fayed, the judges writing in the opinion that the “plaintiffs have not demonstrated a ‘compelling need’ for the requested records.”

4. Zaid Represented Families of Victims Killed In the Bombing of Pan Am Flight 103

1/Please remember #PanAm103/#Lockerbie for 30th anniversary (Dec 21) by helping raise $30,000 for scholarships at @UofR. I was part of legal team that filed 1st lawsuit agnst #Libya in 1993 for murder of 270 innocent lives. We settled case in 2003. I created scholarship in 2005. — Mark S. Zaid (@MarkSZaidEsq) December 13, 2018

Mark Zaid was part of the legal team that represented the families of victims killed in the 1988 bombing of Pan Am Flight 103. 270 people were killed when the plane was shot down over Lockerbie, Scotland. 189 of the victims were American citizens.

An intelligence officer from Libya, Abdelbaset al-Megrahi, was convicted in 2001 for orchestrating the attack. In 2003, the Libyan government agreed to settle civil lawsuits filed by the families of the victims. The government agreed to pay $2.7 billion.

In an editorial for Fox News that was first published in 2013, Zaid explained that he had been part of the case since 1993 and that two of his former college classmates had been killed in the bombing. Zaid wrote that in hindsight, he wished investigators had been more proactive in working to determine if any other countries had bee involved in the attack.

“While the civil lawsuit achieved an unprecedented settlement of $2.7 billion dollars I have always regretted that we never uncovered any new facts. Significant world changes now lead me to question what, if anything, the U.S. and U.K. governments are doing to seek justice for the victims and their families. For example, what role, if any, did Iran or Syria play in the bombing? It cannot be ignored that just five months earlier, a U.S. warship accidentally downed Iran Air Flight 655 with 290 casualties.”

5. Mark Zaid Is a Founding Partner of an Agency Dedicated to Defending Whistleblowers

National Security Whistleblowers: To Be or Not To BeMEL Talks at Meliora Weekend 2014 — Saturday, October 18 in the Louis Alexander Palestra Featuring Mark Zaid '89, Managing Partner, Mark S. Zaid, P.C. Some have accused the Obama Administration of waging a war against Whistleblowers, but who exactly fits within the definition especially when national security is at stake. With the recent massive… 2015-03-13T14:32:21.000Z

Mark Zaid has been practicing law since the early 1990s. Zaid earned a bachelor’s degree in political science from the University of Rochester in 1989. He then attended the Albany Law School of Union University and earned his law degree in 1992.

Zaid focuses much of his practice on whistleblowers. In 2017, he became a founding partner of a non-profit law agency called Whistleblower Aid. He wrote on his LinkedIn page, “No one should have to risk their career or their freedom, to follow their conscience. By making it easier for whistleblowers to expose wrongdoing without breaking the law or incurring criminal liability, we hope to encourage more patriots to come forward.”

Zaid’s bio on the Whistleblower Aid website reads in part, “Since 2009, Mr. Zaid has been named both a Washington, D.C. Super Lawyer every year (including being profiled) and a ‘Best Lawyer’ in Washingtonian Magazine’s bi-annual designation for his national security work. As the National Law Journal once wrote, ‘if Agent Mulder ever needed a lawyer, Zaid would be his man.'”

Zaid serves as the Executive Director of the James Madison Project. The organization was founded in 1998 and its mission is to “educate the public on issues relating to intelligence and national security through means of research, advocacy and the dissemination of information.”

Zaid also is an adjunct professor at Johns Hopkins University. He explained on LinkedIn, “I am currently teaching graduate coursework in Legal Issues in Intelligence & National Security.”

READ NEXT: Kathryn Adams, Rush Limbaugh’s Wife: 5 Fast Facts