In his 42-year career in Congress, Texas Democrat Jack Brooks led efforts to impeach President Richard M. Nixon and to curb federal waste. He died at age 89. (James K. W. Atherton/The Washington Post)

Jack Brooks, who served 42 years in the U.S. House of Representatives as an unpredictable but influential Texas Democrat, and who was one of the few politicians who cast fear in President Lyndon B. Johnson, died Dec. 4 at a hospital in Beaumont, Tex. He was 89.

The Jefferson County Sheriff’s Department in Texas issued a statement confirming his death but did not provide a cause.

First elected to Congress from a southeastern Texas district in 1952, Mr. Brooks became a protege of two fellow Texans, Johnson — then a powerful senator — and Sam Rayburn, the longtime Democratic leader and onetime speaker of the House.

Mr. Brooks became a committee leader in Congress, first of the House Committee on Government Operations and later of the Judiciary Committee, and was so effective behind the scenes that one of Johnson’s former aides told The Washington Post in 1977 that Mr. Brooks was “one of the few men LBJ was ever afraid of.”

On Nov. 22, 1963, Mr. Brooks was with Johnson in the motorcade in Dallas when President John F. Kennedy was assassinated. In the famous photograph taken aboard Air Force One when then-Vice President Johnson takes the presidential oath of office, Mr. Brooks is standing directly behind the grieving first lady, Jacqueline Kennedy.

As a member of the House Judiciary Committee, Mr. Brooks helped write the articles of impeachment against President Richard M. Nixon in 1974 in the wake of the Watergate scandal and was referred to by Nixon as “the executioner.” In the late 1980s, Mr. Brooks served on the House-Senate Iran-Contra committee investigating unauthorized arms-dealing efforts during the Reagan administration.

Mr. Brooks was an old-style politician who favored assertive talk, bold legislative action and a smoldering cigar clamped between his teeth. He was called “the last of his breed” long before he lost a bid for reelection in 1994.

“Jack Brooks was a complete contrarian, a mass of contradictions,” Ross K. Baker, a congressional historian at Rutgers University in New Jersey, said in an interview. “He was a civil rights advocate and strongly pro-gun. He was fiercely combative, but he was someone who could easily cross party lines.”

Mr. Brooks began defying expectations early in his career by refusing to sign the 1956 Southern Manifesto, a pact among Southern congressmen to support segregation. He was one of only 11 congressmen from the South to vote for the landmark Civil Rights Act of 1964.

He was a strong advocate of NASA, whose Johnson Space Center in Houston was for a period in his district. As chairman of the Government Operations Committee from 1975 to 1988, he exposed billions of dollars in government waste. He said the Navy was spending $660 on ashtrays and the State Department had ordered $2 million worth of silverware.

“Brooks finagles and manipulates behind the scenes in the most adroit fashion,” former House speaker Jim Wright (D-Texas) said in 1994. “He knows how to operate, and he will not settle for mediocrity.”

In 1973, Mr. Books questioned the director of the General Services Administration, Arthur F. Sampson, who claimed that $10 million of taxpayer-supported improvements to Nixon’s private homes in California and Florida actually lowered their value.

“Oh, really,” Mr. Brooks said. “Well, Mr. Sampson, I’d like you to come down to my farm and desecrate it a little bit.”

Jack Bascom Brooks was born Dec. 18, 1922, in Crowley, La., and raised in Beaumont. He was 13 when his father died, and began to work odd jobs to help support the family.

After two years at a junior college in Beaumont, Mr. Brooks graduated in 1943 from the University of Texas at Austin, with a bachelor’s degree in journalism. He graduated from law school at the university in 1949.

During World War II, he saw combat with the Marine Corps in the Pacific. He was elected to the Texas legislature in 1946. Six years later, he won election to Congress. For seven of his 21 elections, he ran unopposed.

Survivors include his wife of 51 years, the former Charlotte Collins of Beaumont; three children, Jack E. “Jeb” Brooks, Katherine Brooks Carroll and Kimberly G. Brooks; and two grandchildren.

As chairman of the Judiciary Committee in 1994, Mr. Brooks had helped pass an anti-crime bill that included a ban on assault weapons. He lost his seat to candidate Steve Stockman during the Republican takeover of Congress, after opponents accused Mr. Brooks of advocating gun control.

“I think of myself as someone who tries to be constructive,” Mr. Brooks told The Post in 1977, “someone who understands that politics is the art of compromise, that it’s a lot more important to get something done than get into a lot of battles and get a lot of publicity. All you do is make enemies that way, and who wants to have enemies?”