PHILADELPHIA (AP) _ Pulitzer Prize-winning journalist William Lambert, whose article in Life magazine led to the resignation of a U.S. Supreme Court justice, has died at 78.

Lambert died Sunday at Bryn Mawr Hospital of respiratory problems.

``He is the modern-day father of investigative journalism,'' said former Philadelphia Inquirer executive editor Gene Roberts, who hired Lambert in 1974 and now teaches journalism at the University of Maryland.

Lambert capped his career with a Life report that helped compel Supreme Court Justice Abe Fortas to resign in 1969.

His story, which won the George Polk award for magazine reporting, said Fortas had taken $20,000 in 1966 from stock swindler Louis Wolfson while serving on the bench. Fortas resigned nine days after the story was published.

At the time of the Fortas story, Lambert was Life's top investigative journalist. He became the first member of the magazine's investigative team in 1963 and worked there until the magazine temporarily folded in the 1970s.

Wallace Turner and Lambert shared a 1957 Pulitzer Prize for their five-part series in The Oregonian on corruption in the Teamsters Union. They became the first witnesses in a congressional hearing into the matter.

Another well-known Lambert story described how President Lyndon B. Johnson had used his political clout to build a financial empire.

Turner said Lambert left his mark in journalism by proving he was a well-trusted reporter of integrity.

``He would never consider writing a story until he was completely satisfied of the truth of what he was writing,'' he said.

Lambert left The Oregonian in 1959 for Harvard University as a Neiman fellow. He then joined Life and later the Inquirer before retiring in 1985.

After retiring, Lambert, an expert on courtroom procedure and libel laws, worked as a consultant to many attorneys defending newspapers that were sued for libel, Turner said.

His daughter, Heather Oxberry, said his death was peaceful.

``He was ill quite a while,'' she said. ``It wasn't something sudden.''

Lambert's survivors also include his wife, Jean, another daughter, Cathryn Lambert, four grandchildren and two great-grand children.