Using computer databases, they were able to compare gun usage in major cities.

They found that Washington's Metropolitan Police Department "shot and killed more people per resident in the 1990s than any other large American city police force."

For the first time in the history of the prizes, a single organisation, the Associated Press, won for photography in both the spot and feature categories.

The Associated Press took both photography categories

The press agency won the spot news photography award for its coverage of the embassy bombings in Kenya and Tanzania.

The Associated Press won the feature photography award for its photographs of the people and events surrounding President Clinton's affair with Monica Lewinsky and his impeachment.

The Pulitzer Board gave a special music citation posthumously to jazz giant Duke Ellington on the centenary of his birth.

The board said the award was "in recognition of his musical genius, which evoked aesthetically the principles of democracy through the medium of jazz and thus made an indelible contribution to art and culture."

Prizes online

For the first time in the history of the Pulitzer Prizes, the announcement was carried live on the Web.

This was the first time online exhibits were allowed to be considered in addition to the articles from a newspaper, Pulitzer Administrator Seymour Topping said during the webcast.

The Philadelphia Inquirer submitted their web coverage from its series that explained how local police routinely manipulated crime statistics to make the city appear safer.

It was the only newspaper to do so, Mr Topping said.

The Pulitzer Board will consider allowing online exhibits for submission in other categories in the future, he said.

The Columbia University School of Journalism awards the Pulitzer prizes for excellence in journalism, literature, music and drama.