This time last year, Matthew Klaus was working with Rochester police on an undercover drug investigation.

But the 32-year-old father wasn't an officer. He was a heroin addict who had recently completed his longest stretch of sobriety since he was a child and was attempting to restart his life.

He died of a heroin and fentanyl overdose on March 30, 2019, in between police-sanctioned drug buys, raising fresh concerns about the widespread but opaque practice of using civilians to investigate criminal matters.

His parents, John and Denise Klaus, are taking their fight to the Legislature to ensure no one suffers as their family has. In the wake of their grief, they initiated and helped write "Matthew's Law," which seeks to overhaul the use of informants across Minnesota.

"At one point I thought: No one's looking out for the informant, and somebody needs to," John Klaus said.

"It was really frustrating because it's kind of like they're just throwing people away," Denise Klaus said.

Earlier this month, they told their son's story before a House committee.

"If there had been a policy in effect that was written to protect the informant, Matthew still might be here today," Denise Klaus told the committee.

They could face long odds. Such legislation is rare across the country, and those who have succeeded say they'll likely face pushback.

"They should know that they're keeping his spirit alive and find some solace in knowing this will save other children," said Margie Weiss, who fought for a similar measure.

Weiss and Florida attorney Lance Block successfully introduced the country's first comprehensive law on the use of informants after Weiss' daughter, Rachel Hoffman, was murdered in 2008 while working on a drug investigation. (A law enacted in California in the late 1990s addressed the use of underage informants.)

"Rachel's Law" passed in Florida in 2009. Few others have followed.

"It's a shame that the federal government and states just haven't taken a proactive approach with this in order to prevent some deaths," Block said. "The problem is law enforcement is as addicted to using untrained civilians to do their jobs and go undercover as a drug addict is on the street to a crack rock."

The relationship between police and informants can be complex. Police have said informants can infiltrate criminal circles that undercover officers can't because of established relationships with suspects. Using civilians to work undercover is dangerous, Block said. Civilians can also act as informants by divulging information to police.

He isn't aware of other such legislation aside from "Andrew's Law," which North Dakota lawmakers passed in 2017 after 20-year-old Andrew Sadek was found dead in 2014 while working as an informant.

It often takes a death, Block said, for lawmakers to act.

John and Denise Klaus went to their legislators in November about drafting the bill.

Rep. Duane Quam, R-Byron, authored the measure, which calls for the Minnesota Board of Peace Officer Standards and Training (POST) to consult with law enforcement and treatment and mental health experts to craft a model policy about the use of informants. It would require all Minnesota police agencies to adopt an identical or similar policy and certify it annually with the board, which licenses officers.

Sen. David Senjem, R-Rochester, introduced a companion bill in the state Senate.

John Klaus told the legislative committee he and his wife were compelled to write the law after a Star Tribune article and subsequent news coverage examined the circumstances of Matthew's death.

The Star Tribune found that Rochester police violated their own policy by not seeking approval from probation to hire Matthew Klaus as an informant, a process "Matthew's Bill" seeks to codify. He was serving two probation sentences at the time and had relapsed into substance abuse.

Rochester police Capt. John Sherwin said the department is working on a revised policy that is not publicly available because it has not been finalized. It would mandate "increased supervisory oversight" of informants, internal auditing and counseling with informants about a police program for addiction.

"Matt's death would have gone without inspection except for news reporters," John Klaus said. "We are not aware of any follow-up investigation by [Rochester police] or any other agency, no acknowledgment that a tragedy had happened nor discussions of what might have been done to avoid this in the future."

Mendota Heights Police Chief Kelly McCarthy, chair of the POST Board, said the bill was "well-thought out" and that she supports a model policy, which the board lacks.

Matthew Klaus bought purported heroin three times from Michelle A. Williams and was scheduled to make a fourth buy from her when he overdosed in his Rochester home. Williams, 53, pleaded guilty to third-degree murder for selling him the fatal dose, and is serving a little under nine years in prison.

Matthew Klaus had worked with Rochester police in 2016 as an informant, and approached officers last year to re-establish the relationship. His parents said police told them he wanted to get drug dealers off the street to aid in his sobriety.

Addicts acting as informants are vulnerable to relapse and are likely using drugs during such work, addiction experts have said.

Police pressured Hoffman and Sadek into working as informants by holding their crimes and the threat of prison over their heads. Police found marijuana and ecstasy pills in Hoffman's apartment and Sadek had been busted for selling $80 in marijuana.

Matthew Klaus' family didn't know he was an informant until a friend alerted them two days after his death to articles about Williams' arrest, which referenced it.

"We were not even given the consideration of a phone call from the police department," Denise Klaus told the committee. "… These are people who have families and friends … they should not be used and tossed aside."

John and Denise Klaus never envisioned themselves at the State Capitol fighting for change. After Thursday's hearing they reflected on their testimony and vowed to return as many times as necessary.

"You'll never know how many lives they've saved," Block said, "but they will save lives if this law is enacted."

Chao Xiong • 612-270-4708

Twitter: @ChaoStrib