For years, Philadelphia officials made adjustments in how authorities respond to 911 calls for people in crisis. More police were trained to intervene. Outreach workers were paired with cops in Kensington. And a behavioral health specialist was embedded in the dispatch center.

Then in October, Philadelphia police fatally shot Walter Wallace Jr., firing 14 times at the 27-year-old Black man who approached them while wielding a knife and ignoring calls to drop it. Police were responding to 911 calls with screaming in the background from family and neighbors who said Wallace was hitting his parents.

When police arrived, Wallace’s wife shouted that her husband was “mental,” and family later said he was in crisis that day. But Wallace’s mental health status wasn’t discussed during the frantic 911 calls, and the police’s new behavioral health specialist wasn’t in the radio room when the calls came in.

Pressure almost immediately mounted for city officials to accelerate police reforms they say could prevent deadly outcomes. Mayor Jim Kenney’s administration said it’s poised to take a big step toward that.

Police and behavioral health officials are rolling out a pilot “co-responder unit” program, which pairs a health-care provider with a police officer. The pilot will launch within weeks, and units will operate during the day across a swath of the city that includes Kensington, parts of North Philadelphia, and Center City, areas Police Staff Inspector Francis Healy said have “the most need based on the data.”

The co-responder model has been adopted in cities including Los Angeles and San Antonio, and advocates have pushed it for years as a way to reduce police interactions with people in crisis. A quarter of people fatally shot by U.S. law enforcement since 2015 had a mental illness, according to the Washington Post.

The city and some disability advocates have hailed Philadelphia’s pilot program, saying it will connect residents to services, divert people from the criminal justice system, and de-escalate potentially volatile situations.

But others say the model doesn’t go far enough and advocate removing police entirely, sending social workers and clinicians instead.

Kee Tobar, director of racial equity and inclusion at Community Legal Services, said while she supports the pilot as a step forward, the long-term goal should be non-law enforcement units that can request police only when “extremely necessary.”

» READ MORE: Police killed my mentally ill stepbrother. Now, we have to call police again. | Kee Tobar

The city hasn’t ruled that out. The Department of Behavioral Health and Intellectual disAbility Services already uses mobile crisis units to respond to calls to the Philadelphia Crisis Line. Kenney’s administration has proposed new funding to expand those programs and better integrate them with 911 dispatch.

Community health centers also use mobile crisis units, but are only connected to police informally, said John F. White Jr., president and CEO of The Consortium, a behavioral health center in West Philadelphia. He said while the co-responder units represent “a major step in the right direction,” a successful citywide response will require officials to work more formally with centers like his.

Healy said the co-responder units are part of a broader, layered approach to crisis response in which dispatchers can tap a variety of resources to respond to a call based on how they assess the risk. Late last year, police introduced a new 911 script they say helps dispatchers better identify a mental health crisis.

Multiple response systems can get complicated, so cities must have protocols that clearly establish the types of calls each team responds to, said Daniela Gilbert, director of the policing program at the Vera Institute of Justice, a New York based advocacy and research group. She also said there must be policies on what happens at the scene, including who — the health-care specialist or the officer — decides on care.

Healy said teams are training to navigate the relationship between officer and civilian provider. He said the officers involved in the pilot — who will wear “a khaki-type uniform” instead of the traditional blues — are among the 2,700 cops who have undergone 40-hour crisis-intervention training. (That’s fewer than half the force. The regimen is voluntary, Healy said, as some studies have shown better outcomes in police attitudes when they “self-select” to be trained.)

Police in Bensalem this year started a co-responder program by embedding a social worker and clinician with the police department. Over the last four months, they’ve worked with more than 80 people in distress, some on multiple occasions, said Director of Public Safety Fred Harran. He noted one person has called 911 for help five times in the first few months of this year, compared to 37 times during the same time frame last year.

“This program is working,” Harran said. “It’s going to be the new model for law enforcement.”

» READ MORE: Mobile crisis units in the Philly area take strain off police when dealing with mental-health incidents

Amy Watson, a University of Wisconsin-Milwaukee professor who studies mental health and criminal justice, said co-responder programs have grown popular over the last couple years, but the eventual goal is sending just health-care workers who can request police assistance if necessary.

She said the presence of police when a person already feels vulnerable can escalate a situation, especially in communities of color that have long borne the brunt of police brutality. But for some cities, she said, “there’s this fear that it’s too dangerous to send non-law enforcement.”

Healy said police can get to a scene quickly: “We do have lights and sirens.” And in many cases, police want the backup and understand clinicians are equipped to help a person experiencing a mental health crisis.

In Denver, officials launched a co-responder program in 2016 that has expanded from three mental health workers to 25. Those teams respond when there’s an imminent safety concern, like a person in crisis who could be homicidal.

Last June, the city began piloting a Support Team Assisted Response, or STAR, which removes law enforcement. A paramedic and a clinician work in the city’s downtown area out of a van, responding to behavioral health calls and connecting residents with services.

STAR has responded to about 1,400 calls, and not one has required police backup or led to an arrest, said Chris Richardson, associate director of criminal justice services at Mental Health Services of Denver. He said providers have built rapport with residents, making follow-up more seamless.

He hopes it expands following the yearlong pilot.

“We’re not trying to be an authority,” he said. “We’re trying to support that person and be the support along the way.”