Standing amid the rows and rows of graves at Ft. Rosecrans National Cemetery, Francisca Bacong says she still cannot understand the nightmare that took the life of her only daughter, Navy Lt. Florence Choe.

As the nation today celebrates Memorial Day amid increasing American combat deaths in Afghanistan — 140 this year; more than 1,000 since the invasion in 2001 — Choe's death is proof anew of an immutable fact: War's cruelty is sometimes incomprehensible.

Choe, 35, a hospital administrative specialist, had gone to Afghanistan to help the Afghans establish a hospital for their military and civilians. She was devoted to her husband and young daughter in San Diego, but the call to duty was strong.

She and two other U.S. military personnel were jogging inside the perimeter of the base near Mazar-i-Sharif on March 27, 2009, when an insurgent posing as an Afghan soldier shot all three at point-blank range.

As Choe fell to the ground, the gunman stood over her and fired again. Choe and another Navy officer were killed, the third runner was seriously wounded but survived and the insurgent killed himself as armed U.S. guards came running.

"She went there to help the Afghan people," said Bacong, her voice trembling. "She had asked us to send clothes and chocolate and magazines for them, and we did. And then this happens."

Choe had insisted that she would be in no danger during the 12-month deployment: She was a noncombatant, working inside the security of a base.

She was born in San Diego — her parents had emigrated from the Philippines — and received a bachelor of science degree from UC San Diego in 1997 and a master's in public health with an emphasis on healthcare administration from San Diego State in 2001. She enlisted in the Navy two days after the Sept. 11 terrorist attacks.

After service in Navy hospitals in Okinawa, Japan; San Diego; and Bethesda, Md., she was excited about helping the Afghan government begin to provide decent medical care for its people.

"She kept telling us after she got there, 'Don't worry, Mom and Dad, I'm safe, I'm not doing the fighting,' " said her father, Rufino Bacong, 65, a retired Navy culinary specialist.

The shock of having Navy officials and a chaplain arrive at their home to notify them of their daughter's death is still palpable.

"It was unreal, like I was watching a movie," her mother said. When the details of the killing were later revealed to them, the family's agony only increased.

"To shoot her while she was on the ground," said Choe's husband, Navy Lt. Cmdr. Chong "Jay" Choe, 34, a physician at Naval Medical Center San Diego, "shows us how radical, how extreme many of their thoughts are about us."

On Monday, there will be a small flag on Choe's grave, and on each of the 102,000 other graves at the expansive cemetery in the Point Loma area of San Diego. It's a Memorial Day tradition.

Florence Choe's family members have their own tradition forged from tragedy. They go to her grave every week, sometimes more often, to talk, cry and gather strength from their memories of a bright, loving young woman dedicated to her family and her nation.

"It's peaceful here," said Choe's brother, Rufino "Ruffy" Bacong Jr., 37. "I can talk to Florence here. I feel her presence."

A cousin, Marsha Lapid, 29, works near the cemetery and visits the grave frequently. "It helps me to come here and talk to Florence," she said, her eyes filling with tears. "She's still here for me, still bringing the family together."

To 4-year-old Kristin Bacong Choe, her mother's grave is a "happy place." Last week she brought a small, pink stuffed bear to share with her mother.

On Mother's Day, she brought a card she had drawn for her mother and placed it beside the tombstone. A shy but sturdy child, Kristin offers strength to older members of the family.

"When Florence was killed, I said, 'I don't have any life anymore,' " said Francisca Bacong, 62, who wears a T-shirt with her daughter's picture. "But now I know I have to go on for Jay and Kristin."

Kristin's resiliency amazes her father. "She is my source of strength, she carries on," he said.

While in Afghanistan, Florence Choe had organized other U.S. personnel to videotape readings of their children's favorite books. Kristin occasionally asks that her father play the one of her mother reading "The Cat in the Hat" and "Goodnight, Gorilla."

It would be surprising if Jay Choe did not feel anger at the gunman and the circumstances that led to the killing. But when he thinks about his wife's death, he realizes that the U.S. cannot overcome the hatred and misunderstanding rampant in Afghanistan through force alone.

"It's going to take a lot more than bombs and bullets," he said. "It will take winning hearts and minds. That was what Flo was there for."

To walk the grounds of the 77.5-acre Fort Rosecrans cemetery is to bear witness to the service and sacrifice of generations. Choe's grave is between those of an Air Force veteran of World War II and the Korean War who died in 2008, and a Navy veteran of World War I and World War II who died in 1959.

Down the row from Choe's grave is that of Navy SEAL Michael Anthony Monsoor, who posthumously received the Medal of Honor for smothering a grenade to save his buddies in Iraq in 2006. His gravestone has the motto "No Regrets."

Choe's gravestone notes her Purple Heart and Bronze Star and says that she "graced us with her beauty."

As a military family, Choe's parents know that there will be more fresh graves and more grieving at Ft. Rosecrans next Memorial Day.

"I hope the war is over soon. I hope that they can all come home," said her mother.

"It's going to be awhile," her father said softly. "It's going to be awhile."