OKLAHOMA CITY — It's been 15 years since a terrorist's bomb destroyed the Oklahoma City federal building, killing 168 people and injuring more than 600.
The passage of time hasn't made mourning any easier for many victims' family members.
"Time heals nothing," said Debi Burkett Moore, whose brother, U.S. Department of Housing and Urban Development worker David Burkett, was killed. She and other family members placed flowers on an empty chair meant to honor her brother that's among a field of chairs at the Oklahoma City National Memorial.
"It makes it a little more bearable, but it heals nothing," Moore said.
About 2,000 people gathered at the memorial Monday to honor those killed and injured in the bombing of the Alfred P. Murrah Federal Building on April 19, 1995. At the time, it was the deadliest terrorist attack on U.S. soil.
For many in attendance, a visit to the memorial is an annual rite — a way to pause and remember a loved one, former colleague, friend or neighbor who died.
Kathryn Burkett, the mother of David Burkett, said she grows sadder by his absence with each passing year.
"Why it is sadder? I don't know why," Burkett said. "You just live with it."
Other victims' family members said they, too, still feel a deep sense of grief.
"I don't make it here every year. It's just too hard. It's just like yesterday," said Cornelius Lewis III, who wore a T-shirt and medallion that bore the portrait and nickname, "Puddin," of his late sister, Social Security Administration employee Charlotte Thomas.
"In 15 years, I would never miss it," said her mother, Bettie Lewis. "This is part of our lives. I would never miss it."
Another of Thomas' brothers, Guy Lewis, said his sister's life will never be forgotten thanks to new curriculum guidelines for Oklahoma students that mandate instruction about the Oklahoma City bombing and its aftermath.
"She's going to be in the history books. Her memory is going to live forever," he said.
Vickie Lykins and her sister, Angela Richerson, placed a rose, an American flag and a colorful purple ribbon on the chair honoring their mother, Norma "Jean" Johnson, a former Defense Security Service worker who was killed.
"This is our mother's favorite color," Lykins said as she solemnly secured the ribbon to the chair. Lykins said she misses her mother "very much" but preferred to keep her feelings about the bombing anniversary and her mother's death to herself.
"There's a lot of things we could say. But we won't," she said.
During a ceremony for bombing victims and survivors, U.S. Homeland Security Secretary Janet Napolitano said the city's spirit in the wake of the tragedy served as an example to the nation.
Napolitano also said the bombing anniversary was a reminder of "the continued need for vigilance against the violent ideologies that led to this attack, so that we can recognize their signs in our communities and stand together to defeat them."
"We cannot put a glass dome over our country. We cannot guarantee there will not be another attack. No one can," Napolitano said. "But we are a strong and resilient country. And we can resolve that even a successful attack will not defeat our way of life."
Across Oklahoma City, people observed 168 seconds of silence to honor the dead. Some dabbed away tears as the ceremony closed with family members reading a roll call of those who died.
"What defines us as a nation, as a people and as communities is not what we have suffered, but how we have risen above it, how we've overcome," Napolitano said. "We can resolve that the Oklahoma Standard becomes the national standard."
Attending the ceremony was Charlie Hangar, the Oklahoma Highway Patrol trooper who stopped bomber Timothy McVeigh on I-35 the day of the blast because his 1977 Mercury Marquis did not have a license plate.
Hangar, now the Noble County sheriff, read the memorial's mission statement at the start of the service. U.S. Rep. Mary Fallin, R-Okla., the state's lieutenant governor at the time of the bombing, read a congressional resolution commemorating the anniversary.
Prosecutors said McVeigh's plot was an attempt to avenge the deaths of nearly 80 people in the government siege at the Branch Davidian compound in Waco, Texas, exactly two years earlier.
McVeigh was convicted on federal murder charges and executed in 2001. His Army buddy, Terry Nichols, was convicted on federal and state bombing-related charges and is serving multiple life sentences at a federal prison in Colorado.