When he finishes a regular shift of examining the contours of a murder scene — the shell casings and blood spatter, the mystery of who pulled the trigger — one Philadelphia police investigator begins a new ritual. He drives along a familiar route to his house at the edge of the city, but stops before entering. Inside, he has family members with compromised immune systems, which makes them especially vulnerable to the deadly coronavirus.

He stands, for a moment, in his garage. His clothes are immediately tossed into the washer. His shoes get pushed to the side. He sprints into the shower.

“I can’t take any chances,” explained the investigator, who requested anonymity because he didn’t have approval to speak publicly.

Countless Philadelphians have learned new routines that they hope will protect them from the virus: donning masks and gloves on neighborhood walks, scrubbing groceries with disinfectant wipes, interacting with relatives only through windowpanes.

But for first responders such as police, there’s no getting around the fact that their job puts them at a heightened risk for contracting COVID-19.

The first city employee claimed by the virus was a cop: James Walker, a lieutenant in the Traffic Division, a 59-year-old with a wife and two daughters. Walker’s wife said he was admitted to Abington Hospital-Jefferson Health on March 27. Nine days later, he died.

» READ MORE: Philadelphia police lieutenant dies from the coronavirus, first fatality among city employees

Walker’s death was a reminder that a police officer’s world is often claustrophobic. Cramped patrol cars, shared with a partner. Small, dilapidated district headquarters buildings, where dozens congregate. Narrow streets where they come face-to-face with any number of people every day.

The city has not been willing to release the number of first responders who have contracted COVID-19, but a law enforcement official familiar with the issue told The Inquirer that at least 800 members of the 6,500-strong police department have been “impacted” by the virus, which is to say that they’ve come in direct contact with someone who has the virus, or have traveled to a hot spot, such as New York City.

About 140 have tested positive, the official said. Thus far, Walker is the only police officer whose death has been attributed to the virus.

“I would say, daily operations-wise, the number of people that we’ve had out, that have been impacted, whether personally or someone they’re connected with, has been very low, compared to the number of resources that we have available to use,” Police Commissioner Danielle Outlaw said.

Multiple cops, from rank-and-file officers to supervisors, expressed a range of views on the virus and its impact on the department, echoing the spectrum of public opinion. Some think the threat posed by the virus has been overhyped by the media. Most, though, described a sense of anxiety that pervades their daily lives, and complained that the city isn’t doing enough to keep them safe or informed.

Outlaw isn’t surprised that the rising body count — COVID-19 has killed at least 472 people in Philadelphia — and the ever-evolving wisdom on how to best avoid the virus have rattled some of her troops.

“You’re looking at a very structured profession, with very clear-cut mandates," she said. "It’s a paramilitary organization. When you insert a level of uncertainty, of course it’s going to tweak morale.”

» ASK US: Do you have a question about the coronavirus and how it affects your health, work and life? Ask our reporters.

Though there hasn’t been a department-wide mandate for officers to ride in patrol cars alone, instead of in pairs, some districts have adopted this approach on their own.

“It doesn’t make any sense to be driving around in pairs, when you don’t have enough room to social distance,” said John McNesby, president of Fraternal Order of Police Lodge No. 5. “That’s a concern we’ve been trying to address with the city.”

Outlaw said police brass have explored a variety of approaches to ensure that cops aren’t unnecessarily close to one another, from adjusting shifts to allowing certain personnel to work remotely. They considered a widespread switch to having cops drive solo.

"The bottom line is, we just don’t have enough cars for that,” Outlaw said.

Since March 20 — a week before Lt. Walker was hospitalized after experiencing difficulty breathing — the department has posted more than a dozen coronavirus-related policies and protocols for officers to follow.

One memo directed police to delay making arrests for nonviolent crimes, such as drug offenses, stolen cars and theft. “I got flack for that initially,” Outlaw said, “but now you find folks all over the country doing the same thing.”

» READ MORE: With courts closed by pandemic, Philly police stop low-level arrests to manage jail crowding

Most of the policies underscore the importance of cops wearing protective equipment — gloves, eye goggles, cloth masks, or N95 masks “if available.”

Some bristled at an April 7 memo that called for officers who make an arrest to put “a cloth, paper or other non-N95 mask over the prisoner’s mouth and nose." Officers were also instructed to question everyone they arrest about whether they have the virus, or have come in contact with someone who had it; those who might be COVID-19 positive are being processed at a single police facility in North Philadelphia.

“Where are we getting extra masks from? We don’t even have enough masks for us,” said one supervisor. “And should we be getting that close to someone else’s face?”

Inspector Sekou Kinebrew, a police spokesperson, said the policy “was implemented in order to protect officers and others nearby from possible exposure to the virus from arrested persons.”

But a lack of protective gear was cited by the officers who spoke to The Inquirer as an ongoing problem. Several said that two pairs of eye goggles have been issued to officers who work on wagon crews, transporting prisoners, with the understanding that they will clean the goggles at the end of their shift, and then share them with officers who ride in the wagon on subsequent shifts.

“That could be the result of a shortage of the goggles,” City Managing Director Brian Abernathy said. “I know we’re working on it. Obviously, it’s not ideal. But not a lot of what we’re dealing with is ideal.”

Abernathy said that the city is obtaining more N95 masks, but believes that the police department has a sufficient supply. The city, he added, will likely conduct a review to ensure that the masks have been distributed.

“The majority of officers should have N95 masks,” he said.

The FOP, meanwhile, has spent close to $400,000 on cloth masks, hand sanitizer, and disinfectants that have been given out to cops, according to McNesby.

Some of the officers and supervisors interviewed said they have not received information from the department or the city about coworkers who have tested positive, so they can’t know for sure whether they’ve been exposed to the virus.

“We don’t know who’s tested positive, or who’s self-quarantining,” said one supervisor. “I work around someone who hasn’t been in work in almost a month. I got tested. It came back negative.”

Abernathy cited privacy concerns — “Just because they’re public servants doesn’t mean they give up a right to privacy” — but emphasized that the city is following strict health protocols that require employees to be notified if they’ve come in contact with a colleague who either has the virus, or has been exposed to someone else who has it.

“We’re following the guidelines that we have,” he said. “We understand that officers are anxious.”

Cops grumble about worst-case scenarios: What happens if the virus spreads in greater numbers through the department? How would the force operate if 20% or 30% of uniformed officers became ill?

It’s an unsettling premise — especially since shootings and homicides continue to climb — but not entirely far-fetched. In New York City, more than 4,600 officers have tested positive for the coronavirus, and at one point, nearly 20% of the 36,000-member department was out sick. Officials there are now experimenting with a pilot program to take officers’ temperatures when they report to work at their precincts. But that’s not a foolproof way to identify carriers; fevers aren’t a symptom in everyone who has the virus.

» READ MORE: Even a pandemic can’t slow Philly’s gun violence

Abernathy and Outlaw said the city has a contingency plan for the police department if the virus forces services to be streamlined.

“I’m cautiously optimistic that we won’t get to that point,” Abernathy said. “The department has managed this fairly well.”

Cautious optimism, masks, and gloves. These are the new tools of law enforcement in the age of the coronavirus.