Hilary Campbell, widow of fallen Maine State Police Detective Benjamin Campbell, receives the flag that had draped her husband’s casket, at the end of his funeral on Tuesday at Cross Insurance Arena in Portland. Giving her the flag is Col. John Cote, the chief of Maine State Police. BEN MCCANNA/Portland Press Herald

Maine State Trooper Benjamin Campbell had a guardian’s heart.

On one of the coldest days of the year in Penobscot County, a call came in that someone had dumped several domesticated rabbits at the Medway rest area.

The rabbits, hell-bent on resisting arrest, led Campbell around and around the highway pull-off until he had finally cornered and scooped up all but one of the wayward pets. Tired from the effort, Campbell headed out, leaving the fifth rabbit to fend for itself.

“That’s where the story would end for most of us,” Maine State Police Colonel John E. Cote said, fighting back tears. “But this was Ben.”

Campbell got a mile down the road, but he could not stop thinking about that lone rabbit. He stopped the cruiser and turned around, Cote said. After another hour, Campbell finally captured the last rabbit before delivering the lot of them to an animal shelter.

“At his center, the part that made him special, Ben had the heart of a guardian,” Cote said.

It was that same instinct that brought Campbell to the side of Interstate 95 last week in Hampden. He was helping a stranded motorist on the side of the road on April 3 when he was struck and killed by one of two wheels that separated from a passing logging truck. Campbell, 31, was the first Maine state trooper to die in the line of duty since 1997.

Thousands of police officers, state troopers and public safety employees and relatives gathered Tuesday to remember Campbell, mourn his loss and give tribute to his service at the Cross Insurance Arena in Portland. Representatives from 18 other state police and highway patrol agencies, along with members of the Royal Canadian Mounted Police, attended the tribute to Campbell, said Stephen McCausland, spokesman for the Maine Department of Public Safety.

Campbell, who would have turned 32 on Monday, joined the Maine State Police in 2012 and was promoted to detective in 2016. He worked in the polygraph unit, no longer assigned to patrol Maine’s highways. On the day he died, Campbell was en route to a training session for other troopers when he heard a dispatch call for assistance with a stranded motorist who had spun out on a slippery section of I-95. Campbell answered the call.

In an overwhelming show of support, the hundreds of officers formed a column of blue and black and gray that stretched along Portland’s Spring Street. They stood motionless at attention and saluted Campbell’s casket as the procession rolled toward the arena.

Campbell’s widow, Hilary, held their 6-month-old son, Everett, as they waited for the funeral-draped casket to be removed from a car by six uniformed troopers. She pressed a white handkerchief to her face as her husband’s casket was carried past her into the arena.

Hilary Campbell, who spoke during the funeral through tears and waves of emotion, urged people not to let negativity fill their lives, and to let go of anger and hold loved ones close.

“If there is anything I can say as I try to wrap my head around this, it would be for all of you to slow down, to take life in,” Hilary Campbell said. “Life gets crazy. All things become larger than they should and take more attention than they should. So don’t waste your time on it.”

She also had a message for the motorist, Robert J. Anthony Jr., whom her husband was assisting in the moments before his death.

“I pray that his perfect smile … will be with you forever and ingrained in your mind and your heart,” she said. “I hope it will help your healing, for I know your life is also forever changed.”

Earlier Tuesday morning, buses filled with law enforcement officers from around Maine and from other states flowed into Portland from all directions. Each bus was escorted by police cruisers with lights and sirens activated. Groups of officers also gathered on Commercial Street to line up for the procession to the arena. Inside the arena, other officers rehearsed the funeral ceremony near two State Police vehicles in position to flank Campbell’s flag-draped coffin.

Campbell’s body was transported to a local funeral home Monday in a solemn procession from Millinocket to South Portland. Dozens of police officers and other first responders lined the route and stood on highway overpasses in the snow and rain to pay their respects to Campbell.

Officials closed streets around the Cross Insurance Arena to make way for people attending the funeral and for a procession from South Portland to Portland.

Police continue to investigate how the wheels, weighing roughly 200 pounds apiece, came off the logging truck near the Cold Brook Road exit on I-95. No one has been charged in the incident.

Anthony, the 26-year-old driver Campbell had been helping on I-95, posted on Facebook an open letter to Campbell describing their short interaction and the “warmest of smiles” that the detective wore on his face.

“I vow for as long as I live, I will never forget your smile,” Anthony wrote. “I will never forget your kindness. I will never forget your sacrifice.”