Billionaire hedge fund mogul and major Donald Trump funder Robert Mercer is being sued by a long time employee for criticizing President Trump.

For two decades, research scientist David Magerman worked at Mercer's Renaissance Technologies LLC. His employment ended on April 29, in what he claims was a wrongful termination.

"The dispute started on Jan. 16 when Magerman called Mercer and asked to have a conversation about his support of Trump, according to the complaint," Bloomberg reported. "During the chat, Mercer said the U.S. had started going in the wrong direction 'after the passage of the Civil Rights Act in the 1960s,' according to the complaint. Mercer also said that black Americans 'were doing fine' in the late 1950s and are the 'only racist people remaining in the U.S.,' according to the complaint."

Additionally, the complaint claims Mercer said racial segregation was not an important issue.

"Mercer, a major investor in Trump-friendly Breitbart News, advised the president to hire two of the Mercer family’s longtime political advisers, Stephen Bannon and Kellyanne Conway," Bloomberg continued. "Mercer emerged as one of the most influential Republican donors in the 2016 election, giving at least $2 million to Make America Number 1, a political action committee that began backing Trump in July."

Mercer's daughter Rebekah chaired the Make America Number 1 PAC. Rebekah Mercer was a member of Trump's transition and also features in the lawsuit. It's alleged she confronted Magerman on April 20 at a celebrity poker in New York City, calling him, "pond scum" and saying Karma, "is a bitch."

The lawsuit Magerman v. Mercer, 17-cv-02083 was filed in U.S. District Court, Eastern District of Pennsylvania (Philadelphia).