Richard Junkins lost everything when his double-wide trailer burned down last year. The flames were so severe that his wife fled without shoes, but Junkins would be stripped of more than his possessions.

Hours later, a Madison County, Alabama, sheriff’s deputy killed a member of his family: a 7-year-old black Labrador named Mr. Bear, a canine Junkins called his “son.” After all, the 46-year-old tinkerer, who makes a living off his patents, raised Mr. Bear since adopting him through a “free puppies” sign a few miles from his mobile home.

“They used to call him Beverly Hillbilly,” Junkins said of his dog. “Everywhere I went, Mr. Bear was in the front seat. Every time I went to the store, every time I done anything.”

“He was my son,” the inventor added. “A lot of people laugh at me when I say that kind of stuff … but [the officer] didn’t shoot a bird or a cockroach. They come over and shot and killed my son.”

Moments after Mr. Bear was gunned down, deputy Daniel De Jong arrested an irate Junkins for disorderly conduct. As Junkins tells it, De Jong threw him in a patrol car and cranked up Soundgarden’s “Black Hole Sun,” allegedly to taunt him on the way to jail. The cop refused requests to transport Junkins, on the verge of collapse, to a motel or hospital instead.

Last week, a jury finally found Junkins not guilty of the misdemeanor disorderly conduct charge, yet his fight is far from over.

He wants authorities to take De Jong off the streets for good. He’s written lawyers, the Alabama State Police, and the Federal Bureau of Investigation for help, he says.

To Junkins, it’s De Jong who should be charged with a crime. His police report never mentions killing Mr. Bear, which Junkins declares an obstruction of justice.

According to AL.com, De Jong may also have shot and killed a suspect fleeing from him in January in a use of force questioned by a local civil rights lawyer. (De Jong has not been officially named as the responding officer.)

De Jong is also accused of tasing an African-American engineer three times during a housewarming party in 2013, a lawsuit claimed.

So far, no one has held De Jong accountable for Mr. Bear’s death. Indeed, when asked about the dog, Madison County chief deputy Dave Jernigan told AL.com that the shooting was a textbook example of when to use lethal force.

Jernigan told AL.com it was dark and officers were faced with questions over the use of alcohol or drugs. De Jong was only protecting himself and “did the right thing,” he said.

Mr. Bear’s killing, Jernigan said, could be used in future training for his department—an idea that torments Junkins.

“Somebody’s got to be the voice of reason to make people understand police have been getting away with this for a long time. It’s time to stop,” said Junkins, who gained local fame for creating a paintbrush cleaner called the Paint Piranha.

“This man tried to come on my land the day my house burned down … and he shoots a dog for barking at him,” he added. “He didn’t have pepper spray, a stick … he had his gun out coming onto my property.”

The story of Mr. Bear’s sad fate, as well as larger problems facing the Madison County Sheriff’s Department, were first revealed by AL.com this week.

De Jong responded to Junkins’s property March 6, 2015, about 10 hours after his trailer, just north of Huntsville, burst into flames. A utility worker testified that he called cops after spotting Junkins on the roadside, figuring he was drunk or hurt. The driver was so alarmed by Junkins’s agitated state, he said, that he gripped his pistol, according to AL.com.

Junkins denies he was intoxicated. Rather, he rushed 200 feet toward the motorist to stop him from hitting Mr. Bear, who darted toward the street. Junkins had nowhere else to sit but the roadside; his yard was flooded from fire hoses, his truck was stranded in the mud, and his money was burned up. He had to “start over with spoons and forks,” because everything he’d ever owned was toast.

Making matters worse, the inferno came on the anniversary of his father’s death, after a blanket got too close to a kerosene heater, AL.com reported.

“If you would have cracked my head open that day, steam would have shot out of it,” Junkins told The Daily Beast. “I was mentally sick. I was beyond sick.”

When De Jong rolled in, he shined a flashlight at the smoke-stained trailer, and Mr. Bear ran out from the darkness. Junkins said the dog was about seven feet away when De Jong fired at him.

“Hey! Hey!” De Jong yelled, before pumping bullets into Mr. Bear.

Junkins found Mr. Bear dead and alone on the next day after he and his wife, Angie, returned from jail.

A half-dressed Junkins bellowed, “Son of a bitch ... You shot my dog!” De Jong commanded a frantic Junkins to drop to the ground, and the dog owner replied, “My house burned down today and now you shot my dog!”

At one point, Junkins, whose emotions were running wild after losing both his dog and his trailer, yelled, “Shoot me!”

“This cop comes up on Mr. Bear’s land, and Mr. Bear, he’s an inside dog,” Junkins said. “He never slept outside. He was on his back porch, wanting to lay down in his house on his personal couch, and this cop shines a flashlight on him and spooks him.”

“That’s what dogs do. When you scare them, they’re going to bark at you,” Junkins added. “He shoots a dog for barking at him.”

Footage from De Jong’s body camera, reviewed by local media, appear to show the cop trying to explain away his fatal actions to Junkins.

“We’re trying to figure out what’s going on, I get a big-ass dog running at me, I ain’t going to get bit.”

“You killed my baby,” Junkins tells De Jong while in custody.

In the back of the squad car, Junkins continued to ask, “Did y’all kill my dog?” De Jong responded, “Sir, I don’t know to be honest,” AL.com reported. Junkins sobbed, “Where is Mr. Bear then? Mr. Bear sleeps with me every night.”

The Madison County Sheriff’s Office did not return messages left by The Daily Beast.

At Junkins’s trial, the judge forbade any testimony on Mr. Bear or to allow the jury to see De Jong’s body camera video. Still, it took jurors only 20 minutes to find Junkins not guilty of the misdemeanor charge, according to AL.com.

“They tried to make me out as this drunken bum with no education,” Junkins told The Daily Beast, adding that he only was allowed to mention Mr. Bear in light of flagging down the utility worker.

“And the jury, when they heard what happened that day … these people start coming out [of the courtroom]. patting me on the back and saying, ‘Man, we are so sorry they done you the way they done you.’”

James R. Foley, an attorney for Junkins, described his client as “an honest, down-to-earth person” who is “trying to get justice for what happened to him.”

“The legal system here has turned a deaf ear on him, except the jury who found him not guilty,” Foley told The Daily Beast.

Junkins tried several times to report his treatment to police, Foley said. The lawyer called Junkins’s arrest illegal, since he was charged with a crime—disorderly conduct for obstructing traffic—that occurred before De Jong arrived.

When asked why Junkins was ever prosecuted, Foley replied, “That’s the question I kept asking.”

“Even if you’re not going to prison, who wants to have this hanging over you for a year?” Foley said, referring to Junkins’s year-long wait for trial. “I do not understand why they were adamant about prosecuting him for this.”

Meanwhile, De Jong, who is white, made headlines last year for using a taser three times on an African-American engineer, Dominique Kenebrew, who won a $124,000 settlement with the county, AL.com reported.

In his lawsuit, the 29-year-old Kenebrew said he was hosting a housewarming party in May 2013 when De Jong and a fellow deputy knocked at the door, demanding to enter the home but refusing to state why. (According to police, the cops were responding to a noise complaint.)

Kenebrew stepped outside and told the cops they couldn’t enter without a warrant. When he turned around, De Jong shot Kenebrew in the back with a Taser. Then the officer shot him twice more, according to the lawsuit.

In December 2014, De Jong praised police providing security for disgraced St. Louis cop Darren Wilson, who fatally shot an unarmed black teen, on the Facebook page “Survive the Streets: A Page for Cops.”

“I wanted to take a moment to shout out to our brothers and sisters in the St. Louis area that are providing round-the-clock security to Wolfhunter Darren Wilson,” De Jong wrote. “May the Lord continue to watch your 6, and be with your families as you are away from them extra while keeping our own safe. I am proud to call you all family.”

He signed his post, “An Alabama Brother.”

Junkins emailed authorities, including an FBI agent in December 2015, stating police refused to take a statement on Mr. Bear’s shooting. He noted De Jong’s police report didn’t mention the discharge of his firearm or the killing of an animal as required.

“De Jong is a dangerous person and not qualified to carry a gun,” Junkins wrote, adding, “When he kills a human, all of us will have blood on our hands and then it will be [too] late.”

In January, Randy Joe Sanders, 33, died after being shot by an unidentified cop, whom the sheriff cleared of wrongdoing days later. Law enforcement sources told AL.com this week that De Jong was the officer who shot Sanders. (Chief deputy Jernigan told AL.com that the incident would be presented to a grand jury.)

Police say Sanders fit the description of a suspect behaving erratically at a gas station, and some callers said the man had a gun. The suspect refused to speak to a responding deputy and fled into a subdivision, AL.com reported.

He was shot during a foot chase not long after for refusing “the deputy’s repeated commands to stop and show his hands,” cops said in a press release.

But civil rights attorney Hank Sherrod told AL.com it would appear Sanders was shot in the back as he fled, as police made no mention of him raising a weapon at the deputy.

“Just because you possess a gun, it is generally not enough to warrant being shot,” Sherrod said.