Masks have been a contentious issue throughout the novel coronavirus pandemic.
Should you wear one? Who should wear one? What type? Do they protect you or others or both? How effective are they?
Now a dark new front has opened up in the battle over face coverings, which in recent days became flashpoints in a series of violent encounters across the nation, including a security guard who authorities say was killed after telling a woman to leave a store because she was not wearing a mask.
The heartbroken mother of 43-year-old Calvin Munerlyn, a father of eight killed at a Flint, Michigan Family Dollar store on Friday, had strong words for those defying laws to wear masks during the pandemic, which has killed more than 73,000 people in the United States and more than 264,000 worldwide.
"All you people just have to do is listen to the law, listen to the governor. Just stay home," Bernadette Munerlyn told mourners at a vigil on Sunday night for her son. "If you don’t have to come out, then you wouldn’t need a mask unless you’re out getting groceries or necessities."
Incidents first popped up in February, as the pandemic was raging in China and several people who were wearing masks in the U.S. were accosted -- highlighting fears of bias against Asian and black Americans. At the time, government and public health officials were recommending against wearing masks, saying that they did not protect citizens from coronavirus and should be reserved for medical professionals.
But as governors across the country, including Michigan Gov. Gretchen Whitmer, have mandated citizens wear masks when out in public and the Centers for Disease Control and Prevention advised wearing them when social distancing was difficult, the number and severity of those incidents, while still isolated, has escalated.
The escalation coincides with growing tensions over government restrictions surrounding the pandemic, including stay-at-home orders and keeping businesses closed.
And some law enforcement officials say these confrontations also highlight a tension between personal liberty and public safety, but warn that there are more appropriate avenues for free expression.
In Holly, Michigan, the police chief, Jerry Narsh, recounted another headline-grabbing incident surrounding masks.
On Tuesday night, Holly police officers arrested 68-year-old Rex Gomoll on an assault charge after he allegedly wiped his nose and mouth on a Dollar Tree store clerk's shirt when he was told to wear a mask, Narsh said.
"There’s been fear and apprehension, but I think the greater issue is that everyone has felt a total loss of control in their adult lives and as they begin to be allowed to go back into open society, there’s this sense of empowerment, a sense of 'taking control of my life again,'" Narsh said.
However, he added that resisting laws and requests from businesses for people to wear masks "is the wrong battle to pick to feel in control again."
Gomoll was arraigned on Wednesday via video conference on a misdemeanor charge of assault and battery, Narsh said. A judge set bail at $2,500 and ordered Gomoll to be placed on home confinement.
The suspect did not immediately respond to a request for comment from ABC News.
Narsh said there were signs posted at the entrance to the Dollar Tree advising customers are required to put on masks before entering the store.
"Certainly he had a right to voice his opinion about wearing a mask and he had a right to go to another business instead of shopping at that one," Narsh said. “But he did not have a right to wipe bodily fluids on the body of another person."
In February, as the virus was beginning to spread from hot spots in China and Europe, a series of confrontations occurred in the United States in which people wearing masks were targeted. No arrests have been made. At the time, the virus appeared to be largely contained overseas and there were fears of anti-Asian bias as a result of the virus's origin in China.
An Asian woman wearing a mask was attacked by two men and called "diseased" in a subway station in New York City's Chinatown, according to the New York Police Department (NYPD). Four people were arrested in March in Hilton, New York, after they allegedly punched and taunted a woman for wearing a respirator mask in a store, according to the Monroe County Sheriff's Department.
MORE: 2 McDonald's employees shot after angry customer told dining room was closedMen of color have faced a particularly daunting choice during the outbreak -- don't wear a mask and potentially put yourself or others in danger from COVID-19 or wear a mask and potentially make yourself appear threatening.
In Wood River, Illinois, two young black men, Jermon Best and Diangelo Jackson, recorded a viral YouTube video in March of a police officer not wearing a mask following them around a Walmart and then kicking them out for wearing masks. "We're being asked to leave for being safe," Best said in the video. The incident is under investigation.
Now attacks are occurring over people not wearing masks:
-- On Friday, a 56-year-old man was arrested in Decatur, Illinois, after he allegedly shoved a gas station clerk who asked him not to enter the station's mini-market without a mask on, Sgt. Brian Earles of the Decatur Police Department told ABC News. Earles said the incident escalated when the suspect was told the station didn't have change for a $100 bill the man was using to pay for gas and the man attempted to leave without paying. He said the clerk ended up punching the man leading police to arrest both men on battery charges. Neither have entered pleas.
-- The Mayor of Stillwater, Oklahoma, last week reversed an emergency proclamation requiring shoppers to wear face masks after the mandate prompted a flurry of threats of violence. Mayor Will Joyce amended the policy on Friday after employees at businesses allowed to reopen were "threatened with physical violence and showered with verbal abuse" in the span of three hours, Stillwater City Manager Norman McNickle said in a statement. There was one threat of violence using a firearm, he added.
-- On April 21, a 20-year-old woman in Wilkes-Barre Township, Pennsylvania, was arrested for creating what police described as an “extreme disturbance” by allegedly attacking a store manager who barred her from entering for not wearing the mask she had dangling around her neck. The suspect was arrested on suspicion of obstructing justice, disorderly conduct, providing false identification, and violating health department orders to wear a mask, Wilkes-Barre Township police said in a statement.
-- And on April 26, a 33-year-old woman was arrested for allegedly attacking a grocery store employee in St. Clair Shores, Michigan, after being ordered to leave for not wearing a mask, according to the Macomb County Prosecutor's Office. The woman was charged with assault and battery, felony obstructing police officers and refusing to be fingerprinted.
Jean Cloud, the acting Macomb County prosecutor, described the incident in St. Clair Shores as "incomprehensible" and an insult to essential workers, adding that the suspect also allegedly spit on police officers, requiring them to get tested for COVID-19.
"With everybody out there trying to provide a service that is so desperately needed during a time when everybody is in lockdown, you'd think they would be praised and put on a pedestal," Cloud told ABC News. "And then you have these people who are absolutely above and beyond disrespectful and committing criminal behavior abusing the people who are just trying to provide a necessary service to the public. This is the very behavior that nobody wants to see during a pandemic or at any time."
The violent incidents have also come amid the backdrop of open-the-economy protests in Michigan and throughout the nation, in which demonstrators have defied stay-at-home orders, many showing up at rallies not wearing masks and refusing to practice social distancing. Some have even carried rifles.
Many of the Michigan protesters have vented their anger at Gov. Whitmer, who has imposed some of the most stringent stay-at-home orders in the nation, including banning the use of motorboats and travel to and from vacation homes in the state, and naming landscaping companies and plant nurseries among the non-essential businesses that must remain closed.
It remains unclear if any of the violent incidents that have erupted over masks in Michigan stemmed from Whitmer's orders.
MORE: FBI warns of potential surge in hate crimes against Asian Americans amid coronavirus MORE: Isolation of families for coronavirus raises concerns about domestic violenceMixed messages from government leaders may have fueled some of the backlash against wearing masks. The CDC and the White House Coronavirus Task Force initially advised against wearing masks unless people were showing symptoms of the disease, then later flipped and advised people to wear face coverings in public when social distancing is difficult. States also changed their stances on masks, with New York recently requiring face coverings in public and maintaining a 6-foot distance from others.
President Donald Trump, who has refused to wear a mask in public, has expressed support on Twitter for anti-lockdown protesters, some who have displayed re-elect Trump signs at rallies. Vice President Mike Pence, who is spearheading the White House Coronavirus Task Force, stepped into a controversy last week when he was photographed at the Mayo Clinic in Minnesota not wearing a mask.
At their daily coronavirus briefings, New York City Mayor Bill de Blasio and New York Gov. Andrew Cuomo have emphasized the importance of people wearing masks to avoid spreading the virus (the rule became effective April 17). The two leaders have also expressed outrage and exasperation over people who still prefer not to wear a mask despite the virus having already accounted for nearly 14,000 confirmed deaths in the nation's largest city alone.
MORE: Backlash against Asians could hinder efforts to contain coronavirus, expert saysDe Blasio has gone so far as to announce that the city is handing out 7.5 million free face coverings to New Yorkers through May 12.
"Just wear a mask. It’s the responsible thing to do. It’s the right thing to do," Cuomo said on Tuesday. "I don’t understand why people think it’s a burden to wear a mask."
Genessee County, Michigan, Prosecutor David Leyton said Calvin Munerlyn certainly should not have lost his life in Flint for telling someone to do the responsible thing and cover their face in public.
On Monday, Leyton announced that three people had been arrested and charged with murder, including Sharmel Lashe Teague, 45, the woman who police allege traded heated words and spit on Munerlyn when he told her to either wear a mask or leave the store, Leyton said at a news conference. After Munerlyn kicked Teague out of the store, the woman returned with her husband, Larry Edward Teague, 44, and son, Ramonyea Travon Bishop, 23, Leyton said.
He said Bishop allegedly gunned down Munerlyn.
"Decisions like staying home when we can, wearing a mask when going to the store and staying a safe distance from those around us, these should not be political arguments. They don't necessitate acts of defiance and we simply cannot devolve into an us-versus-them mentality," Leyton said.
"We really need to make a commitment as a community ... to doing the things necessary to allow us to stay healthy and turn the page on this crisis altogether," Leyton added. "If not for ourselves, we should do this for Calvin Munerlyn, who has lost his life needlessly and senselessly."
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