CORSICANA, Texas — Brent Thompson was training to join the Dallas Area Rapid Transit motorcycle corps, and wanted his friend William Franklin to affix his pin signifying the certification when the time came. It never did.

Instead, at a vigil in Thompson’s heartbroken hometown, Franklin and his wife, Shonna, presented the pin to Thompson’s family.

“Brent was very special to our family,” Shonna Franklin said during the vigil. “These last few days have been extremely tough. A lot of sleepless nights and so many emotions.”

With Dallas preparing for Tuesday’s visit by President Barack Obama and former President George W. Bush, the vigil Sunday night for Thompson was just a preview of the outpouring of grief yet to come. Texans will say goodbye to Thompson, a 43-year-old newlywed, and the other four officers killed Thursday night by sniper fire in downtown Dallas. His funeral and those for Dallas Police Senior Cpl. Lorne Ahrens, Officers Michael Krol and Patrick Zamarripa and Sgt. Michael Smith are coming this week.

Thursday's ambush came at the end of a peaceful protest in Dallas. Protesters had gathered in reaction to fatal police shootings of two black men in other states.

Micah Xavier Johnson, 25, the suspect in the Dallas attack, was killed after police negotiations failed.

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“There is no possible justification for these kinds of attacks or any violence against law enforcement,” Obama said from Poland, where he had been attending a NATO summit.

Bush posted a message of condolence on his official Facebook page:

“Laura and I are heartbroken by the heinous acts of violence in our city. Murdering the innocent is always evil, never more so than when the lives taken belong to those who protect our families and communities.

Bush went on to praise Dallas Police Chief David Brown and Mayor Mike Rawlings.

“We join our fellow citizens in saluting the fine law enforcement officers in Dallas and across the country who put their own lives on the line to keep all lives safe.”

Police officers from neighboring Arlington, Texas, will assist the Secret Service to provide security during the presidential visit, Brown said during a news conference Monday. He didn’t want his emotionally devastated and physically fatigued department to have to take on that duty.

Security was tight Sunday at the vigil in Corsicana, a town of about 25,000 roughly an hour south of Dallas. Law enforcement officers stationed on the high school’s roof kept watch during the service while many officers, including Thompson’s grief-stricken fellow DART officers, were among the mourners who lighted candles and sang “Amazing Grace.”

“I never had a brother before. If I did, I like to think he would have been just like Brent,” said DART Officer Robert Kiser. “He meant the world to me. He talked about his family every time we were on patrol together. Brent Thompson was my brother, and I loved him.”

Thompson’s family members attended but requested privacy from media covering the event. His brother, Darrell Thompson, spoke on their behalf.

“We know we’ll see him again,” he said.

His brother was serving as a civilian in Iraq, training police officers, when Darrell’s daughter Samantha was born. The newborn had to have surgery, and her parents were understandably rattled.

“My phone rang and I expected it would be a nurse. It was Brent, calling from Iraq,” he said. “He said, ‘Don’t worry, she’s a Thompson, she’ll be fine.’ He was in a hostile land, trying to comfort me. He is a hero. Our family already knew that. Everyone knows that now.”

Corsicana Police Chief Robert Johnson appealed to the public to support law enforcement.

“Please stand together and say this explosive rhetoric and confrontational attitudes are not acceptable,” he said. “I ask all official and unofficial leaders to be proactive in guiding those who would act on pure emotion. Let’s use our maturity and wisdom and not inflame the situation.”

Corsicana is in Navarro County. Sheriff Elmer Tanner also touched on the tensions between law enforcement and the citizens they serve, stoked by police shootings elsewhere.

“Law enforcement is under stresses today unlike we’ve ever experienced,” he said. He was moved by the people who stood along the route into town when Thompson’s remains were brought home.

“I’ve been a law enforcement officer in this community for over 28 years,” Tanner said. “I have never in my life been touched in a manner that I was in bringing our fallen brother home to our city. The outpouring and showing of love — it was a sight to behold and a fitting tribute to such a fine young man that’s gone too early.”

He gave an emotional farewell to his friend: “Rest easy, my brother. We’ll take it from here.”