John Doar, a civil rights attorney who led the investigation of the Watergate scandal as special counsel, died at his Manhattan home on Tuesday, the 92-year-old’s son Robert told The New York Times. The cause of death was described as congestive heart failure.

Doar grew up in Wisconsin and played a vital role during the civil rights movement in the 1960s as a lawyer with the justice department between 1960 and 1967. During his time as the assistant attorney general for civil rights, Doar fought to end racial segregation in the South and spoke up for the rights of African Americans.

"As the face of the Justice Department in the segregated South, John escorted James Meredith to the University of Mississippi. He walked alongside the Selma-to-Montgomery March. He laid the groundwork for the Civil Rights Act and the Voting Rights Act," President Barack Obama, who awarded Doar with the Presidential Medal of Freedom in 2012, said in a statement Tuesday, adding: "Time and time again, John put his life on the line to make real our country’s promise of equal rights for all."

In 1974, Doar was named chief counsel to the U.S. House of Representatives Judiciary Committee investigating the Watergate scandal, which resulted in the resignation of Republican President Richard Nixon.

The self-described "Lincoln Republican" was also reportedly involved in the investigation of the murders of Michael Schwerner, James Chaney and Andrew Goodman, three civil rights workers who were killed in 1964 in Neshoba County, Mississippi, for helping blacks register to vote. The incident reportedly inspired the 1988 film “Mississippi Burning.”

“John Doar, one of the bravest American lawyers of his or any era,” Obama said, in the statement, adding: “Without John’s courage and perseverance, Michelle and I might not be where we are today, and our thoughts and prayers are with his children, his grandchildren, and all those who loved and admired him.”

Here are some tweets by politicians remembering Doar.