Authorities Escalate White House Attack Case : Violence: Francisco Martin Duran is charged with attempting to assassinate President Clinton. The suspected gunman pleads not guilty.

Federal prosecutors on Thursday escalated their case against the man accused of peppering the White House with gunfire last month, indicting Francisco Martin Duran on a charge of attempting to assassinate President Clinton.

U.S. Atty. Eric H. Holder Jr. told reporters that “we have sufficient information now” to support the more serious charge, even though officials repeatedly have said Duran fired randomly at the White House on the afternoon of Oct. 29 and that Clinton was never in danger.

The charge, brought by a grand jury, carries a maximum punishment of life imprisonment, a much harsher sentence than those Duran faces under the 10 charges previously lodged against him, including weapons violations, destruction of federal property and assaulting law enforcement officers.

Duran, 26, pleaded not guilty to the attempted-assassination charge Thursday afternoon in an appearance before U.S. District Judge Charles R. Richey. The judge gave Duran’s lawyer, public defender Leigh A. Kenny, until early next week to disclose if she is planning an insanity defense.

Holder refused to divulge any specific evidence supporting the new charge except to suggest that it is based largely on statements given to the FBI by several people who knew Duran in his home state of Colorado and on observations by people in Washington.

The charge is supported “by what people said Mr. Duran said while he was in Colorado,” Holder said. It will become clear at Duran’s trial, that “he attempted to take action to assassinate the President,” he added.

At the time of the shooting, Clinton had just returned from a trip to the Middle East and was watching a college football game on television in the family living quarters on the opposite side of the White House from Pennsylvania Avenue, where the attack took place.

Although no one was injured, at least eight shots chipped the exterior of the White House and the adjoining West Wing, where Clinton has his office, and broke a window in the press briefing room.

Duran was subdued on the sidewalk by two passersby. Secret Service agents rushed to seize him several moments later.

Attempted murder normally is a state crime, not a federal offense, but Congress has provided stiff penalties for the murder or attempted murder of a President or other federal official.

The attack, which occurred six weeks after the apparent suicide of a Maryland man who crashed a small aircraft onto the South Lawn, has spurred an intensive study on ways to improve presidential security. Recommendations are due in January.

Referring to the Duran case, Holder said: “The fortuitous outcome of this disturbing incident does not serve to allay our concerns about the security of our elected officials and those who protect them and does not diminish our resolve to hold accountable those who seek to place them in jeopardy.”

Holder said he was disturbed that more people who knew of Duran’s intentions had not exercised their “moral duty” by reporting the information to authorities.

Government sources have said a map found in Duran’s pickup truck after the shooting had a phrase on it that may have said “kill the President.” The third word is unclear, although it appears to be a misspelled abbreviation for “President,” they said.

Associates of Duran told reporters in Colorado that he had talked about going to Washington to “take out” the President. Duran, a hotel employee, was dishonorably discharged from the Army last year after serving a prison term for felonious assault.