A police radio crackles, and Washington County social worker Hannah Driver listens in. If the call is for a person with a mental health crisis — about one-fifth of all 911 calls, studies show — Driver might hustle out the door with her partner, a detective with the Washington County Sheriff's Office, to go help.

The person on the other end of that call could be an addict struggling to shake free from their addiction, a person riding out a wave of extreme paranoia, or someone who's just lost their job and, along with it, their will to live.

"No person-in-crisis call is ever the same," said Driver, who started working with the Sheriff's Office last year.

This is the "co-response" model of social workers embedded in law enforcement, a growing strategy in Washington County and across Minnesota as reform-minded police departments answer calls for change — and explore new methods of handling mental health emergencies.

Driver, along with Sheriff's Office detective Matt O'Hara and Deputy Julia Weegman, is on track to make contact with about 500 people by the end of this year. She's one of three social workers embedded with law enforcement in Washington County; Angie Shackleton has been with the Woodbury Police Department for just over two years, and Nicholas Pilney joined the Stillwater Police Department in July.

The extra help has been welcomed by police chiefs and county sheriffs, in part because data shows that a small number of people struggling with mental health can account for an outsized demand on officers' time. A social worker can divert someone to therapy or to other services that may be more appropriate than sending them to jail and tying up the criminal justice system with people not facing charges.

It can be safer for the person in crisis if they feel less threatened when their call for help brings a social worker in civilian clothing, rather than a gun-toting officer in uniform. Some 23% of people killed by police nationwide since 2015 were mentally ill, according to a Washington Post database.

"Every department should have this," said Stillwater Police Chief Brian Mueller. "It's a great partnership."

Police officers can't be all things for all crises, said Mueller.

"Gone are the days we expected police officers to be everything, to have medical knowledge, to be jack of all trades," he said.

The Stillwater department pairs Pilney with detective Chyrisse LeMoine. The partnership works well, though there are logistical challenges: Pilney has access to social services databases and case worker information, while LeMoine sees criminal records and investigations. Mueller said it needs to be easier for responding teams to quickly access all relevant information.

"That lies with the Legislature to open up the avenues to get us to talk to each other. There's more work to do on that for sure," he said.

The early success of embedded social workers has Washington County prepared to spend $1.7 million to keep the three social workers already in place while adding six more over the next three years.

The county would pay 75% of the social worker's salary for the first year, and then split the cost with the city.

In Woodbury, Shackleton said she and detective Adam Sack have gone out on calls dealing with substance abuse, domestic violence and homelessness — situations she encountered when she previously worked with the county's crisis response unit, which had a 24/7 mental health hotline. Now that she's with the police, she's on the front lines.

"It's really boots-on-the-ground social work," she said.

The county still has its crisis response unit, staffed by civilians, but they're more likely to get engaged when someone voluntarily calls for help.

It was a good start, said Jen Castillo, the county's director of human services. But by working with law enforcement, social workers can reach more people in crisis. A call to 911 brings the co-responders, while a call to 988, the national mental health hotline, goes to the county's civilian-staffed crisis response unit.

"A lot of people won't come to us," said Castillo. "We have to meet them where they're at."

For example: An unsheltered and chemically dependent young adult generated a lot of 911 calls over drugs and criminal activity, but Driver and O'Hara were able to persuade him to go into inpatient treatment.

"They were able to develop a trust with this individual and avoid any sort of incarceration," said Castillo.

Driver, the social worker, works typical day hours during the week, and some of her job requires looking through 911 calls from the previous night. If she sees someone she knows from previous contacts, she might reach out to see how they're doing.

O'Hara, the sheriff's deputy who teams up with Driver, said safety is always a priority. "The detective isn't going to put [the social worker] in a situation where it's starting to turn in the wrong direction," he said. "She knows she can always leave."

But O'Hara said he's also adopted some of the social worker's approach: He might dress in civilian clothing, keeping his badge and a gun tucked away. He'll use an unmarked squad so that if he responds to someone's home, the person doesn't face the shame of having their neighbors see a sheriff's car in their driveway.

"We're not trying to intimidate somebody or make them nervous," said O'Hara.

A man they've been working with was calling 911 five or more times per week, reporting things he had seen and heard in a state of paranoia. Once O'Hara started visiting him routinely, the man's 911 calls dropped to one or two a month. O'Hara and Driver bring a tablet to help the man check his court dates and avoid ending up with a warrant for his arrest.

In another case, a person well-known to O'Hara and Driver with a significant mental health history was reported for trespassing within Washington County but outside of the sheriff's jurisdiction. O'Hara was able to call the police department that was about to respond and share the best way to approach the man.

"It could have gone one of two ways with him and it could have turned volatile," said O'Hara.

Instead, the police were able to talk to the man, and he was sent home in a rideshare.