March 25, 1996 12:00 PM

FOR 40 YEARS, LARRY LOCKRIDGE rarely spoke of the absence that has dominated his life. “I never told people I was the son of Ross Lockridge Jr.,” he says. That might seem a curious omission, since the elder Lockridge wrote Raintree County, the 1948 literary sensation hailed by many critics at the time as the Great American Novel. But just months after the book was published, when Larry was 5, Ross killed himself. “If I mentioned him,” says Larry, now a professor of literature at New York University, “I’d have to spend all day talking about suicide.”

It was partly to disentangle the two ideas—his father and self-destruction—that Lockridge, 53, wrote Shade of the Raintree: The Life and Death of Ross Lockridge, Jr. The book helps bring alive a figure heretofore remembered more as “a literary suicide,” says his son, than as a gifted author. But Lockridge also hoped to solve the mystery: Why would a man apparently at the top of his game choose to end it all at 33? “It hit me one day that I had to write this,” says Lockridge.

The family’s “founding catastrophe,” as Larry calls the suicide, occurred on March 6,1948, at the Lockridge home in Bloomington, Ind. Ross Jr.—generally “one of the most balanced, cheerful people,” his son says—had been depressed over editorial cuts made to Raintree, his mythic, life-affirming account of an Indiana boy’s search for his roots, and had decided it wasn’t the masterpiece he had thought. Telling his wife he was going to the post office, he headed for the garage, turned on the ignition and let the carbon monoxide do its work.

Until he was 11, when his mother, Vernice, filled him in, Larry, the second of four children, thought the death was accidental. Vernice, a homemaker, had initially “followed protocol, which said children should be protected,” he says. Once he knew, says Larry—whose clearest memories of Ross are of his “typing or singing while he did dishes”—he felt sorry for his father. “I learned sympathy,” he says. Thanks to his mother, who explained that Ross had had a breakdown but spoke often of happier times, Larry also learned to revere him. “And when I read Raintree, I didn’t see any imperfections,” he says. “In a sense, I grew up with a novel instead of a father.”

The void had its effect. “If he had lived, I think I wouldn’t have gone into literature,” says Lockridge, who received a B.A. in literature from Indiana University and a Ph.D. from Harvard before going to teach at NYU in 1978. “It would have been too much.” His temperament was influenced as well. Though Larry has never been clinically depressed, “the offspring of suicides tend not to be very assertive—you suffer a diminishment,” he says. “My siblings and I are quite shy.” (He and Ernest, 57, a musician, Jeanne, 51, a college administrator, and Ross III, 49, a painter, remain close.)

Deciding to write his father’s biography, though, required boldness. “I had to go with anything I found out, even if it was horrific,” he says. He interviewed his siblings and Vernice, who were enthusiastic about the project, and spent two years collecting enough of his father’s letters to fill three file cabinets in his Greenwich Village apartment. (Married briefly in college, he has been single since.) He discovered that Ross Jr. was “a perfectionist” who didn’t drink, adored his family and “didn’t have affairs,” says Larry. “I felt proud to be his son.”

As for what drove him to suicide, Larry believes the letdown after Raintree was finished brought on a depression to which Ross was genetically predisposed. (Two years earlier, Ross’s cousin Mary Jane Ward had written the bestseller The Snake Pit, about her own manic-depression.) He was given shock treatments in late 1947, but his psychiatrists released him after two weeks. “Today’s drugs,” Larry says, “might have saved him.”

Larry’s siblings and his mother, who died of lymphoma at 80, three months after Shade was published, were delighted with his book. “Mom hung on just for that,” says his sister Jeanne. Raintree County, out of print for decades, has been reissued, and Larry is happy about that, as he is about his own book’s reviews (“an American classic,” declared the Boston Globe’s Richard Dyer). He has experienced none of his father’s despair. “I think I’m dealing better with my modest success,” he says quietly, “than he dealt with his overwhelming one.”