BRUNSWICK (Ga.) — A few months before Ahmaud Arbery was murdered, shooter Travis McMichael posted a chilling Facebook response about a possible car burglary in his Georgia neighbourhood: “Arm up.”

He commented on the item in between chats about lost dog and water service interruption. This is typical of many U.S. online communities that are based around physical neighborhood.

However, McMichael’s posts from the subdivision where he lived in 2017 show a neighborhood that was more concerned about low-level incidents. Residents were able to share suspicions, keep their children safe, and become more willing to take matters into themselves.

Online neighborhood forums in the U.S. can have a disturbing tendency to diverge from normal community chat to anxious hypervigilance when discussing suspicion.

It makes people more anxious, hypersensitive or on-alert. Pamela Rutledge, a media psychologist, stated that it makes people more suspicious of others not like them. It’s really a way of stacking the kindling because people then watch for anything to go wrong.

Monday’s closing arguments will be heard in the murder trial of McMichael, and two other white men accused in the killing of Arbery. This death was part of a wider reckoning of racial injustices in the criminal justice system.

After seeing Arbery, a 25-year-old Black man run in their neighborhood near Brunswick, Georgia in February 2020, Travis McMichael and Greg McMichael took out guns and chased him in a pickup truck. William “Roddie”, Bryan, joined the pursuit in his truck and took cellphone video of Travis McMichael’s shooting at Arbery while he threw punches, grabbed for the shotgun, and continued the chase.

They claim they were trying to stop illegal burglaries in their area, and McMichael testified that he shot Arbery in self defense.

He also stated that he learned a lot about burglary reports in the Satilla Shores area from the Facebook group. This was where he lived with both of his parents.

His “arm up” comment was in response to a July 2019 court document in which a woman warned of car burglaries and said: “Remember that you can’t determine if a theft is a lightweight murderer or a lightweight.”

A November item mentioned a Black man recording with a white couple on back-toback nights in a home five houses below the McMichaels. Travis McMichael responded: “They really are playing with fire.”

All sides agree that the Black man in question was Arbery. He was captured on video five times in the same house, including before the McMichaels started their pursuit. However, prosecutors claim there is no evidence that he was involved with any crime in the area.

One neighbor testified that she saw a post about a car burglary and decided to check her husband’s truck. She found some tools missing. Brook Perez said it “felt like a violation.”

Lindy Cofer, a neighbor, said that people on the Facebook group shared theories and suspicions about who might be responsible. Cofer denied that she has been a victim to crime in more than 30 years.

According to David Ewoldsen (a Michigan State University professor who studies psychology and media), scholars have known for a long time that fear is a common emotion in people who consume lots of media. Local news has the strongest impact because people are familiar with the area and can identify with it.

It’s closer to home on a neighborhood site and “magnifies” the effect, he explained.

Fear is a response that humans have. People may feel compelled to respond to a situation if the spark is a post on social media from a friend. Ewoldsen stated that all of this is intertwined and will increase the chances of violent responses.

Outright violence is still rare. This year, residents in wealthy Danville, California took to Nextdoor to call for Tyrell Wilson’s removal. A separate rock-throwing incident led to Wilson being shot in the head by a police officer.

Steven Renderos (executive director of MediaJustice) said that these platforms “serve as platforms to amplify and echo a sense that your community is being under attack.” He felt that there was a way white vigilante-ism can be praised, and a way Black existence is criminalized by watching discourses.

Renderos stated that Nextdoor worked with its moderators to reduce racism. An emailed request from The Associated Press to comment on this story was not answered by Facebook.

Renderos still wants to know more about the demographic data of users to determine if it represents the whole community. Artificial intelligence is only capable of weeding out hate speech and violent language.

He said that “at the end of the day,” he stated, “what you cannot fix on the platform side are the racism that exists within those communities.”