Ms. Corrie, a student at Evergreen State College in Olympia, Wash., joined the International Solidarity Movement in January, 2003, and spent the last weeks of her life in Rafah, the Gaza town that borders Egypt. In a Feb. 27, 2003, e-mail home, she wrote that 600 homes had been destroyed there since the start of the intifada. On March 16 she and seven other American and British activists acted as human shields, dropping to their knees between the bulldozers and a home they believed were marked for destruction. The verdict came more than a year after the last of 15 sessions of oral testimony, which began in March 2010. Some of the witnesses, including the drivers and commanders of two bulldozers that were operating in the area that day, testified from behind a screen to protect their identities. Ms. Corrie’s parents or sister attended every session of the trial, spending about $200,000 on travel, translating about 2,000 pages of documents, and other expenses.

“A lawsuit is not a substitute for a legal investigation, which we never had,” Ms. Corrie’s mother, Cindy Corrie, said at Tuesday’s news conference. “The diplomatic process between the United States and Israel failed us.” The United States Embassy, which sent a representative to the oral-testimony sessions, declined to comment on the verdict. In June 2004, a representative of the secretary of state wrote to the Corrie family saying the United States agreed with them that the military’s investigation was not “thorough, credible and transparent.”

In Washington, the State Department’s spokeswoman, Victoria Nuland, said, “We understand the family’s disappointment with the outcome of the trial,” and noted that American diplomats “have worked with the family all through this process” and that they would continue to do so. She declined to discuss the remarks that Ms. Corrie’s family attributed to the American ambassador that the Israeli investigation had not been transparent. But on Tuesday, Hanan Ashrawi, a member of the Palestine Liberation Organization’s executive committee, said in a statement that the United States government “has been noticeably absent, and its silence is deafening,” calling Washington “complicit in compounding the crime.” She also said that the trial had revealed “overwhelming proof that Rachel was deliberately murdered” and said that “Palestinians as a whole will continue to love Rachel and cherish her memory.”

Sarah Corrie Simpson, who has met with more than 200 Congressional offices in Washington about the case, said she remained convinced that the driver of the bulldozer saw her younger sister. “I hope someday he will have the courage to sit down in front of me and tell me what he saw and what he feels,” Ms. Simpson said.

In an interview before the verdict, Ms. Corrie’s father, Craig Corrie, said, “You don’t really close a wound like this, but it certainly is a big milestone.” At meetings across Israel over the past week, Mr. Corrie carried with him a picture not of his daughter but of the Palestinian girl, then 6, whose family’s house was behind Ms. Corrie when she was killed.

“I think this one in some ways is more hopeful,” he said of the picture. “She deserves a future that we all want for our children.”