Thousands of Italians have paid final respects to an intelligence agent killed in Iraq Friday, as the hostage he helped free alleged U.S. troops may have deliberately targeted her.

The body of Nicola Calipari, hailed as a national hero, lay in state in Rome before a state funeral Monday.

A senior White House official (White House Counselor Dan Bartlett) Sunday called his death a "horrific accident" and again promised a full investigation.

Earlier Sunday, freed journalist Giuliana Sgrena disputed the U.S. military's account, saying the car carrying her to Baghdad airport had not been speeding and was fired upon without warning.

Ms. Sgrena also suggested the United States may have deliberately targeted her because it opposes negotiating with kidnappers. The Italian agriculture minister said it is likely a ransom was paid to free Ms. Sgrena.

The press freedom group Reporters Without Borders has called for a U.N. investigation into the shooting incident.