When master K-9 trainer Paul Bryant retired in 2015 after, as he puts it, "33 years, two months, and 28 days" as a Philadelphia police officer, he tried to stay retired.

"I really did," he said, reminiscing with Chester County Sheriff Carolyn Bunny Welsh in her West Chester office.

"Drove your wife crazy," Welsh said.

"Drove me crazy, too," Bryant admitted. "I was 56, retired. I told my wife, Lisa, 'I'm not going to wear a uniform, carry a gun, or work a dog again.' I stayed retired for five months. And here I am" -- military-sharp in a black SWAT-style Chester County sheriff's uniform with "CADAVER K-9" in big white letters on the front.

Since he arrived with his German shepherd, Don, in August 2015, "he's elevated us to another level," Welsh said of her deputy.

Bryant joined forces with Lt. Harry McKinney to create the Chester County sheriff's first-ever K-9 patrol and narcotics-training course -- the only such in-house program in Philadelphia's four suburban counties. Before, the department's dogs were schooled and certified in Ohio, then put in trainer McKinney's hands for continuing education.

The course, Welsh said, is a giant step for her department, which had only two bomb dogs in 2006 and now has 10 K-9s. Mostly German shepherds, they are trained for 400 hours over 10 weeks in obedience, patrol, and scent work (narcotics, explosives, fire accelerants) at locations in Chester County. Other suburban law enforcement agencies train K-9s at the Philadelphia Police Department, and in New Jersey and Baltimore.

Most K-9s come from European breeders, arrive between 11 months and 3 years old, and must have a strong "play drive" -- a fearless desire to investigate unfamiliar places, motivated by the reward of playing tug-of-war with the handler afterward, McKinney said. Such exceptional animals are worth $16,000 to $18,000 each, and are the alpha dogs of their devoted deputies' households.

They first learn to sniff out narcotics and explosives hidden in one of 208 holes on "The Wall" near the department's prisoner loading dock. They then progress to "Tactical Village" buildings and streetscapes at the Chester County Public Safety Training Campus in Coatesville, and to Wolf Hollow County Park and Nottingham Park, where they track trainers hiding in the fields and woods.

The Chester County Sheriff's Office serves a half-million people in 67 municipalities -- 53 of them with their own law enforcement agencies, but only one, West Caln Township, with its own K-9 bomb dog. The public safety departments of West Chester University and Lincoln University each have a K-9.

"We average 100 calls a year per dog," McKinney said, ranging from K-9 demonstrations at schools to criminal arrests like one he will never forget.

Last June 17,  McKinney sent Deputy Ryan Barr and his K-9 partner, Murphy, to assist a Parkesburg police officer who was pursuing an armed suspect fleeing from a drug arrest in a residential area. Arriving at the scene, Barr commanded Murphy to bark. The suspect quickly emerged from an alley 25 feet away, stared at Murphy, surrendered, and said, "Y'all [expletives] would not be able to catch me, but that officer would, and I ain't playing with that."

A German shepherd's bite is 238 pounds of pressure per square inch, McKinney said. "The only way a dog can catch you is to grab you with his mouth and pull you to the ground. That's why the respect a dog gets from a bad guy is a different kind of respect."

Bryant has been finding cadavers with his K-9 partners since 1998. "The biggest reason I do cadaver work is for closure," he said. "You see the faces of a loved one's family, and it melts your heart."

His first cadaver dog, Azeem, discovered the remains of Kimberly Szumski, a missing New Jersey woman buried behind a basement wall in Society Hill, and won the U.S. Police Canine Association's 2001 Detector Case of the Year Award.

Last year, Bryant's current partner, Don, now 3, won best cadaver dog in the country at the USPCA's National Detector Dog Trials. Deputy Brian Bolt and Yukon placed second in explosive detection, and McKinney and Jessie placed Top 15 in narcotics detection. "It took the Chester County Sheriff's Office and made us high-profile," Welsh said.

Bryant sighed. "Don is the dog I needed when I was 30 years old and I was energetic," he said. "I'm getting too old for this. Don will be my last police dog." Welsh and McKinney looked at him in disbelief.

Apart from field work, K-9s are vital at the Chester County Courthouse, Welsh said. McKinney's black Lab, Melody, plays with children to relieve their stress over testifying in custody cases.

"When there's a trial and the jury's out deliberating, it can become contentious between the defendant's family and the victim's family," Welsh said. "When the verdict comes in, someone is not going to be happy. But you put a deputy and his German shepherd between the two groups, and nobody moves."

There are other reasons that Welsh loves her deputized dogs. "K-9s never call in sick," she said. "They're always happy to see you. They never file a grievance. If I could teach them to drive a car, I wouldn't need deputies."