On March 30, 1985, friends found the bodies of Derek and Nancy Haysom in their home in Bedford County, Virginia. Derek was 72 and Nancy was 53. Their throats were slit from ear to ear. The double murder terrified their small, central Virginia community. And it could have political repercussions to this day.

At issue is Tim Kaine’s decision to extradite the Haysoms’ killer, Jens Soering, to Germany. The move would have substantially reduced his prison sentence if Kaine’s successor hadn’t blocked it. Kaine’s allies say he made the right decision for the right reasons. But Virginia Republicans say Kaine’s efforts to extradite Soering could hurt his vice presidential bid—especially given the tough-on-crime focus of Donald Trump’s campaign.

The Haysoms were retirees living outside Lynchburg, Virginia, when the crime occurred. They disapproved of their daughter, Elizabeth Haysom, dating Soering. Soering was a German national, and the two met while attending the University of Virginia. One night, Soering came to their home, had an altercation with them, and then stabbed them both to death—leaving their mangled bodies nearly decapitated.

Investigators initially had trouble finding their killer and didn’t immediately suspect that Elizabeth and Soering were involved. As the investigation proceeded, the pair fled the country, ultimately ending up under arrest in the United Kingdom a year later on check-fraud charges, as The Roanoke Times detailed in a retrospective piece looking at the crime and its fallout.

Soering eventually confessed to murdering the Haysoms and later said he thought diplomatic immunity would give him some protection from the law (his father was a low-level German diplomat stationed in Atlanta and Detroit). Both were convicted and given lengthy sentences; Soering for first-degree murder and Elizabeth for accessory to murder before the fact. A judge sentenced Soering to serve two consecutive life sentences. He’s currently incarcerated in Virginia’s Buckingham Correctional Center.

Since his conviction, Soering has converted to Catholicism and written extensively about criminal justice issues. He says he is innocent and that he only confessed to try to protect Elizabeth. He has tried to get extradited to Germany, where he would serve two years in prison and then be eligible for parole. And he became a cause célèbre in some circles. The late Walter Sullivan, then the retired Catholic bishop of Richmond, backed his extradition and discussed it with Kaine, according to the AP.

And in the final days of his governorship, in January 2010, Kaine moved to extradite Soering. Immediately after being inaugurated, his Republican successor, Bob McDonnell, blocked the move.

Kaine’s effort angered some close to the case, including Ricky Gardner. Gardner is a major in the Bedford County sheriff’s office, and he worked on the team that investigated the Haysoms’ killing. Gardner said Kaine didn’t notify law enforcement or the Haysoms’ family before moving to extradite Soering. (Family members could not be reached for comment; at least one who Gardner said disapproved of Kaine’s move is now deceased.)

Gardner said Soering’s extradition would have resulted in his serving less time than Elizabeth Haysom—even though Elizabeth didn’t actually kill anyone and Soering did.

“If the parole board in their wisdom paroled Elizabeth next week and then Jens Soering the following week, that’s just the way the system works,” Gardner said. “But for her to serve one day longer sentence or stay in jail one day longer than him is a complete travesty of justice. And if Kaine had gotten his way, that’s what would have happened.”

To this day, Kaine’s decision still disturbs Gardner. Kaine publicly defended the move by saying he didn’t want Virginia to carry the expense of Soering’s incarceration.

“He is not a sympathetic character, that’s true,” Kaine told the AP in an interview that ran May 5, 2011. “I would never grant him clemency. But I did feel like Virginians have paid for his incarceration for a very long time. Let the Germans pay to keep this guy.”

Gardner said he doesn’t find that answer satisfactory.

“That’s a bunch of crap,” he said. “Now think about it: If that was the truth, why didn’t he come out and say that back then?”

Kaine didn’t defend his decision at the time he made it. As the AP reported, Virginians only learned of it when The Roanoke Times broke the news just a few hours before his term as governor ended.

Larry Roberts, who was his chief of staff at the Democratic National Committee at the time, said Kaine’s calculation involved more than just questions of cost-cutting.

“My understanding was that he had had a lot of inquiries about it from the German government, including the German ambassador, and at the end of the day, he felt that it would promote the security of U.S. nationals abroad who run into trouble with the law if the U.S. was willing to engage in the international transfer process,” he said.

“It wasn’t the most popular decision that Gov. Kaine made,” Roberts added.

Amy Dudley, a spokesperson for Kaine, said he made a careful decision about supporting the extradition process.

“After receiving assurances from the German government that Jens Soering had been convicted to a life sentence in Germany, and would never be allowed to enter the U.S. again, then-Governor Kaine recommended the Department of Justice consider transferring him into the German penal system where his own country could pay for his life imprisonment rather than Virginia taxpayers,” she said. “He has had no involvement in the case since January 2010.”

Internal emails from Kaine’s gubernatorial administration—which the Library of Virginia has made publicly available—indicate his communications director, Lynda Tran, saw the move as a way to earn the U.S. a favor from Germany.

“OFF THE RECORD and not for attribution you can say that the DOJ looks upon these types of transfers with other nations favorably because it puts us in a good position should there be American citizens held abroad that we wish transferred home in the future,” she wrote to spokesman Gordon Hickey. “We’re essentially logging a favor for the US.”

Virginia Republicans don’t see that as reason enough to justify Soering’s extradition, and they criticized Kaine for it during his 2012 Senate contest. That year was a Democratic wave, and Kaine won the race (as he has every other election he’s ever run in). But Republicans say this year, it could be more of a liability for him because it fits into Trump’s law-and-order narrative.

“We have a lot of things from Tim Kaine’s past, being that he’s been around for a while,” said John Whitbeck, the chairman of the Republican Party of Virginia. “Obviously it’s not the only issue, but it’s one that we plan to highlight.

“Tim Kaine, one heartbeat away from the presidency, has a serious deficiency when it comes to protecting the citizens of the commonwealth—and, in turn, the American people—from what ought to be a slam dunk for him in terms of decision-making with these types of criminals,” he added.

And Clinton’s top ally in the Old Dominion hasn’t helped Kaine on the issue. Terry McAuliffe, a longtime Clinton confidant and the state’s current governor, decided late last year not to extradite Soering.

For his part, Soering won’t appreciate being politicized. When Republicans brought the case up during Kaine’s Senate campaign, he wrote a Washington Post op-ed saying they were trying to make him “the Willie Horton of 2012.”

There’s a big difference, of course; Horton was black, and Soering is white. Still, using the release of a criminal to hit a political opponent worked quite successfully for George H.W. Bush’s campaign in 1988, when the notorious Willie Horton ad ran.

The Republican strategist behind that move? Lee Atwater, whose old business partner—Paul Manafort—now runs Donald Trump’s campaign.