The 7th and 8th books in Malzberg's vigilante series, The Lone Wolf, originally published by Berkley Books in the early 1970s under the name "Mike Barry."
Burt Wulff has gone beyond fear, beyond love, even beyond hate. He's simply beyond giving the slightest damn whether he lives or dies, so long as he can kill the killers - thousands of them, all over American and all over the world. He is the lone wolf.
"Hang on for a wild ride through the dangerous darkness of America in the Seventies!"-George Kelley