After more than three decades and three police investigations, Steve Johnson’s fight for justice in his brother’s death culminated with just three words last Monday: “Offender in custody.”

The short message came to Johnson from the police commissioner in the region of New South Wales, Australia — who had called him a few days prior to say investigators were getting ready to make an arrest in the 1988 killing of his brother, Scott.

“I get a call from the commissioner and I think, ‘How can there be an investigation at a time like this?” Johnson recalled. “It was unbelievable, literally unbelievable, especially that they got it done during COVID-19.”

Scott Johnson had been living with his partner in Sydney when his naked body was found at the bottom of a beachside cliff, with his clothes folded at the top. Police quickly ruled his death a suicide, but Steve Johnson was skeptical.

Then a few years later — when he learned of a history of gang’s attacking gay men in Sydney and at least three other cases of gay men found dead near cliffs around Sydney in the 1980s — he pushed investigators to reopen his brother’s case.

Over the years, Johnson hired an investigative journalist, met with lawyers and travelled to Australia repeatedly to search for answers in his brother’s death. In 2012, He successfully petitioned to have his cause of changed from suicide to “open finding.” In 2015, police launched a third investigation. And two years later, Scott Johnson was declared the victim of an anti-gay hate crime.

Johnson told Jim Braude on WGBH News’ Greater Boston that, in all that time, he never considered dropping his brother’s case.

“I’m not sure I predicted that we’d actually get this outcome, but I never felt like giving up,” he said. “I think Scott would’ve done the same for me.”

Johnson said he hopes the breakthrough in his brother’s case helps investigators solve the deaths of the other gay men killed in the area.

“[The New South Wales Commissioner] went after Scott’s case, not just for justice for Scott, but because of the several dozen other cases that have never been solved,” he said. “All the men who died deserved a voice and I really hope, in some small way, Scott provided one.”

Johnson, who founded a tech company and lives in Cambridge, said his brother was “one of the brightest mathematicians of his generation.”

“They used to say in my family, ‘Steve’s passable, but Scott’s the smart one,’” he said. “Everyone described Scott the same way, kind, gentle and smarter than the rest of us.”