There’s a new member of the Santa Rosa Police Department, and he works for treats. Diesel, a 2-year-old Belgian Malinois, arrived this month to begin training with his partner, Officer Michael Paetzold.

The story of how Diesel got to Santa Rosa, however, began some 14 years ago in San Jose where a skateboard-loving 10-year-old boy wanted to take home the German shepherd he saw at the pound. Young Sean Walsh got what he wanted, said Cheryl Walsh, his mother, when they took home the nearly 2-year-old dog and named her Lena.

Pet ownership sparked a bigger dream for Sean Walsh — the kind of boy who would stand up for bullied classmates, according to his mother — and that was to be a police officer, a K-9 police officer to be exact.

His dream led him to stints as an Explorer cadet for police departments, including in Santa Clara, where Walsh became well-known and popular. At age 18, signed up for the National Guard, where he enrolled as a military policeman.

That was in 2008 in the midst of the U.S. war in Afghanistan, at a time when a good portion of American troops were reservists. Walsh signed up with the understanding he would likely be sent overseas, but he went with a sense of excitement his mother remembers even now.

“He loved being a soldier,” Cheryl Walsh said. “It wasn’t that he wasn’t afraid, but he had a really strong desire to help people and he felt he was doing that over there.”

He planned to use his experience in the military to become a police officer when his tour was over, she said. He even asked her to send him the California state penal code so he could memorize it, which, his fellow soldiers told her, he pretty much did. But 10 days before he was scheduled to come home, Walsh was killed in a rocket attack by insurgents.

The loss was unfathomable for Cheryl Walsh, who had raised her only son on her own, the two so close that they would finish each other’s sentences. But almost immediately after his death in November 2011, she struck on a way to give her son a fitting memorial.

“We have to buy a dog,” she told her partner, Rolando Wehbe, on the way back from meeting Walsh’s casket in Dover, Del., where the bodies of servicemen killed overseas are first flown before eventually being turned over to their families.

She didn’t mean to replace Lena, who is still part of the family, but to buy a police dog for a department that needed one. At her son’s funeral, she found plenty of people who wanted to donate. She also found a department in need. Members of the Santa Clara police force showed up to pay tribute to Walsh and told his mom they were in fact looking to purchase a new dog.

That’s how the Sean M. Walsh K-9 Memorial Foundation was born.

“We started asking for donations before his funeral,” said Cheryl Walsh, 55, a pharmaceutical saleswoman. “We were a fund at first before eventually becoming a nonprofit. It all happened so fast.”

The foundation raises and donates funds to police departments to purchase police dogs — where and what kind of dog is up to the individual departments.

Since its inception, the foundation has helped five police departments get K-9s, including Santa Rosa’s purchase of Diesel.

Word about the program has traveled fast. Sgt. Ryan Corcoran, who supervises the K-9 team for the Santa Rosa Police Department, heard about it from colleagues at the Novato Police Department, who heard about it from their dog trainer, who heard about it from Santa Clara.

For Santa Rosa, Diesel’s addition came at the right time, following the retirement of one of the department’s dogs this summer. Corcoran said the department has four teams of dogs and handlers. “We were fortunate that Cheryl’s foundation was able to help us,” he said.

It can cost $15,000 to $20,000 to buy, train and equip the dogs.

The Walsh Foundation raised $7,500 for the purchase of Diesel, who came from the department’s dog trainer, Heritage K-9. Any other costs involved, including training, equipping and housing the dog, is borne by the city.

Officer Paetzold, Diesel’s partner, has been waiting four years to become a handler. He has spent much of that time working as an “agitator” or decoy with the K-9 team. That means donning a “bite” suit so the dogs can practice subduing or finding suspects in cars or buildings.

“I’m really excited about getting this spot. I worked hard to get it,” Paetzold said. “I hope to follow in the footsteps of the other handlers we’ve had in our department.”

Diesel will live with Paetzold and the pair will participate in a five-week field training program before they hit the streets on patrol.

“It gives them a chance to get to know each other,” Corcoran said. “It’s how they develop trust.”

Diesel arrived in Santa Rosa on Aug. 4, four days before what would have been Sean Walsh’s 24th birthday.

Cheryl Walsh said she’s never been much of a believer in crazy coincidences, but starting a nonprofit in the wake of her son’s death has changed that. When she talks about the dogs her foundation has helped police departments obtain, she loves to list what she calls the “weird connections” to her son. Like the first dog they donated to Santa Clara whose name is Argo, a district in Afghanistan, and that Diesel’s handler’s first name — Michael — is Sean’s middle name.

“I try to believe there’s some bigger reason why this happened,” she said. “And these kinds of things occur, and I can’t help but think that it’s all proof that this is what he would have wanted.”

You can reach Staff Writer Elizabeth M. Cosin at 521-5276 or elizabeth. cosin@pressdemocrat.com.