C.P. Ellis, 78, whose metamorphosis from Ku Klux Klan officer to civil rights activist was described in the 1996 book "Best of Enemies" and a subsequent documentary, "An Unlikely Friendship," died Nov. 3 at a hospital in Durham, N.C. He had Alzheimer's disease.

Mr. Ellis's "enemy" and "friend" of the book and film titles was Ann Atwater, a black advocate of desegregation in Durham.

The event that converted the city's oft-praised "odd couple" from adversaries to allies was a 1971 community discussion about the violence occurring as Durham tried to integrate its schools. Mr. Ellis and Atwater co-chaired the 10 days of 12-hour talks, forging not only the unusual friendship but profoundly changing Mr. Ellis's deeply rooted segregationist thinking.

Mr. Ellis and Atwater had been such bitter foes that she once pulled a knife on him at a Durham City Council meeting, and Mr. Ellis brought a machine gun to their first 1971 discussion session.

They became such close comrades that, after the meetings, Mr. Ellis renounced his position as exalted grand cyclops of the KKK, repudiated segregation and joined Atwater in working to desegregate the Durham school system. They continued to speak jointly at civil rights seminars and meetings for three decades.

When Osha Gray Davidson's book was published in 1996, Atwater told the Raleigh, N.C., News & Observer that Mr. Ellis had become "part of my family" and that she wished others could work together just as well as to end racial strife.

"Ann and I were really thrown together and forced to work together," Mr. Ellis told the Durham Herald-Sun in 1999. "During those days it became clear to me that she had some of the identical problems that I had and that I'd suffered like she had and what in the hell had I spent all my life fighting people like Ann for?"

Claiborne Paul Ellis grew up in poverty in Durham, the son of a millworker. He married at 17 and quickly fathered three children, the youngest born blind and retarded. Despite working two jobs, he could rarely pay the bills. "I worked my butt off and never seemed to break even. They say abide by the law, go to church, do right and live for the Lord and everything will work out. It didn't work out. It kept gettin' worse and worse. I began to get bitter," Mr. Ellis told columnist and author Studs Terkel.

The Pulitzer Prize-winning Terkel interviewed Mr. Ellis twice for such books as his 1992 "Race: How Blacks and Whites Think and Feel About the American Obsession."

"So I joined the Klan," Mr. Ellis told Terkel. "My father told me it was the savior of the white race. I'll never forget the night when they put the white robe on me and the hood, and I was led down the hall and knelt before the illuminated cross. It was thrilling. Me, this poor little ol' boy Claiborne Ellis, a nobody, felt like somebody."

When Atwater pulled the knife on Mr. Ellis, he had just urged the City Council to adopt apartheid-like rules that would, in part, keep blacks, for whom he used an offensive term, off the Durham streets.

After Mr. Ellis began championing desegregation in 1971, he was ostracized by angry white former colleagues and became such an outcast that he considered suicide. Instead, the redeemed Duke University janitor went back to school, received his high school diploma and became a successful union organizer -- in a union with a majority of black members.

Survivors were not immediately known.

Desegregation activist Ann Atwater and former Ku Klux Klan officer C.P. Ellis were opponents in Durham, N.C., for a while, but then he became an ally.