Every year on her wedding anniversary, Barbara Behrend made a call to the Minneapolis Police Department. She was looking for any new information about the killing of her husband, Joseph.

The keyboardist for Minneapolis rock band the Flamin’ Oh’s, Joseph Behrend was slain in his apartment in the early morning of Aug. 19, 1989. The 36-year-old musician had been bludgeoned to death with his own guitar. A suspect was arrested, but without enough evidence to charge him, the case went cold.

For decades, Barbara longed for closure — or at least assurance that the police hadn’t forgotten Joseph, a balding, big-hearted musical prodigy. So she kept calling.

Last March, she got a call back.

Sgt. Jane Moore with the MPD was spearheading a reorganization of the cold case unit. She hoped that by applying today’s forensic technology to decades-old evidence, she could crack Joseph’s case.

Barbara once again would have to share details about her and Joseph’s rocky romance amid Minneapolis’ fast-paced, drug-fueled music scene of the ’80s. Worse, she would have to relive her anguish over losing him in such a brutal way.

She thought, “Screw it, I’ll do it.” Friends who had never forgotten his killing were aging; others had died. “This is the last chance we have,” she decided. “It shouldn’t end like this.”

In a warehouse on the edge of Minneapolis, boxes filled with yellow and pink duplicates are stacked next to mounds of evidence: furniture, luggage, bicycles — and Joseph Behrend’s prized red Epiphone guitar. This is where Sgts. Jane Moore and Chris Karakostas look for answers.

As the force behind the MPD’s rejuvenated Cold Case Squad, they pore through old files and follow leads in cases that reached the limits of what science could — and witnesses would — tell them. Over time, though, labs have gotten better; people loosen their tongues, “and the answer,” Karakostas said, “is probably in that box.”

With the popularity of true crime stories such as the podcast “Serial” and Netflix’s “Making a Murderer,” the MPD is tapping into a cultural moment with the Cold Case Squad. Since its launch last March, it has premiered slick videos about several cases on the MPD’s new website, InsideMPD.com. The videos have a dual purpose: soliciting tips from viewers and boosting the MPD’s image.

“This is a visual world,” Moore said. “Everybody is on social media. Why not use it to our advantage as well?”

Karakostas landed in the Cold Case Squad after solving a case he had investigated years earlier, as a beat cop. In 1998, a young couple were killed in their apartment on Christmas Eve. Karakostas never forgot it. After he doggedly pursued DNA testing that led to an indictment, the FBI funded a position within the MPD for him to investigate other unsolved cases.

Since then, his desk, which he calls a “trash house,” has been overtaken by boxes from the evidence warehouse.

Moore, who studied cold case units around the country, devised a system for methodically revisiting cases year by year — digitizing evidence, unearthing new DNA samples, reinterviewing witnesses and searching for new clues.

“It’s the hunt,” Moore said. “When a fresh murder happens, you’re moving really quickly. On a cold case, you’re at the beginning of the woods and you’re just entering.”

Cold cases rarely end with the satisfaction of putting a perpetrator behind bars, though. Karakostas estimates that only 1 percent of cold cases ever get closed, compared with 60 to 75 percent of current cases. But seeing the hope the work gives to victims’ families is enough.

“To see the delight when a case is solved, that it does give these families some closure,” Moore said, “that’s what drives me.”

• • •

Barbara met Joseph at a show at the Prom Ballroom in St. Paul. For them, music and romance always went together. Barbara worked the door at the Flamin’ Ohs’ touring gigs when she wasn’t bartending at the Cabooze in Minneapolis. The couple married in Miami while the band recorded a third album. Instead of a ring, she bought him a Casio keyboard.

As Joseph’s star rose, the partying got harder, and Barbara and Joseph’s relationship frayed. They were living separately, but remained close, when Joseph was killed.

“Whatever our personal relationship ended up as, this man loved me more than any human has ever loved me in my life,” Barbara said.

After the funeral, an acquaintance told Barbara that if she hadn’t left Joseph, he’d still be alive. All these years later, she hasn’t been able to forget the exchange.

“I know it’s not true, but it stuck in my head,” she said. “I need this to be solved, because I need it to go away.”

Barbara never understood why the case stopped in its tracks. Police say that there wasn’t enough evidence and that they were inundated with homicides at that time.

Barbara suspected it was the disappearance of Jacob Wetterling about two months later that eclipsed the publicity surrounding the slaying of a well-known musician.

Only two stories in the Star Tribune touched on Joseph’s death in the days afterward; then, his name disappeared from headlines.

Now, because of a second look by the Cold Case Squad, there’s a new “person of interest” in the case.

“We’ve had breakthroughs,” Moore said. “Now we need more.”

• • •

The squad’s efforts have given new hope to other survivors, including the family of Tina Slaughter. The young North Side mother was stabbed in her home by a burglar in 1985. For her mother, Patricia Slaughter, the pain of Tina’s death hasn’t faded.

“It’s something that you live with daily,” she said.

Around the 30th anniversary of Tina’s death, her brother Courtney Slaughter rallied his family to press harder for answers. He and his brothers walked into MPD headquarters around Christmastime, when Moore happened to be working a night shift. The squad took on the case, and began retesting evidence from the scene.

Just a few weeks ago, DNA tests revealed the presence of another person in Slaughter’s home. Now the squad has something to go on.

That news is helping heal old wounds. The tragedy “kind of put a little ripple” in the fabric of their once close family, Courtney said. “But during the last few weeks, we’ve gotten a little closer. We’re all working together and talking a lot more,” he said. “It kind of resembles that old family, before this happened.”

The breakthrough was more than the Slaughters — and police — expected. Solving a cold case is a delicate process that takes more of what these cases have already given: time.

“Oftentimes, where your evidence and your interviews lead you is right back to the starting point,” Moore said.

But the squad has learned to find other ways to measure success.

“I never feel like it’s done,” Moore said. “But I do feel like I did the best I could for this moment.”

That might have to be enough. Moore retired at the end of July, leaving Karakostas as the only detective who is devoted full-time to cold cases. (Other homicide detectives rotate into the squad when they have time.)

Despite her retirement, Moore has vowed to continue working on the Behrend case for as long as it takes, because, she said, “It’s not something you want to let go.”

• • •

Joseph Behrend left the Flamin’ Oh’s a few years before his death. Still, he had remained good friends with his former bandmates.

Robert Wilkinson, the lead singer, remembers the classically trained keyboardist as a quirky character and a skilled cook who once whipped up Thanksgiving dinner in the band’s RV while on tour.

Their bond, forged from years of making music together, was unbreakable, he said. Even in death.

“There’s an exchange of energy that musicians and artists have,” he said. “And when you’re in a room creating music, that person is always with you. There will always be a part of him that’s always inside of me, and in some of the music that I write.”

Since the Cold Case Squad picked up Joseph’s case, Barbara Behrend is closer to finding closure. Even if there are no charges, no trial, no killer put in jail, she is ready for the peace of mind that comes with knowing what happened.

“I’ll sleep better,” she said. “I’ll be able to tell my friends it’s OK. And I’ll know I did right by him.”

Moore and Karakostas admit that the case may never be closed. Until it is, Joseph’s beloved guitar — strings broken, battered from blunt force — will remain in a police warehouse, out of sight.