Spree killer and ex-police officer Christopher Dorner was recently mentioned in a standup comedy piece by Dave Chapelle. If the name sounds vaguely familiar, it’s because Dorner killed four people and wounded three others in mid-February 2013, his victims including police and civilians in the Los Angeles area.

The manhunt for Dorner over the course of several days provides real-world insight into eyewitness reliability. As police tracked him down they received eyewitness reports of Dorner in dozens of places around southern California. Heavily-armed police officers descended on a Kentucky Fried Chicken outlet in Tarzana after a tipster said Dorner might be inside; an innocent African-American man who barely resembled Dorner was arrested and soon (thankfully) released.

Dorner was soon spotted at a Lowe’s home improvement store in Northridge, causing the store to be evacuated and a SWAT team dispatched, but he wasn’t there either; he was also reported at Men’s Central Jail in downtown Los Angeles, and so on. The fact that a $1 million reward was offered for information about Dorner’s location understandably increased the public’s incentive for reporting any and all potential sightings.

The public can often be instrumental in helping find missing persons—it is how Elizabeth Smart was eventually recovered after being abducted from her Salt Lake City home in 2002. But it also leads to many false leads. In 2002 two snipers attacked the Washington, D.C., area and terrorized much of America. Based upon eyewitness descriptions, law enforcement agencies alerted the public to be on the lookout for suspects in a white van. Thousand of vehicles were stopped and searched, jamming highways for miles. The focus on a white van intensified after a shooting outside a store in suburban Virginia, when a man claimed to have seen the shooter standing next to a white van. The man later admitted that he lied to police, likely seeking media attention.

While some false sightings are reported as pranks or for attention, most are from sincere eyewitnesses trying to help out. Elvis Presley sighting jokes aside, it is a real problem for police. It is not uncommon, especially in high-profile hunts for fugitives or missing persons, for dozens or hundreds of sightings to be reported to law enforcement. Police, of course, must treat all sightings and reports as potential leads; ignoring a valid tip might cost lives.

Furthermore, because false accusations often target minorities, it’s especially dangerous. You may recall Susan Smith, the mother who in 1994 blamed an African-American man for kidnapping her children when she in fact drowned them in a lake. Or Jennifer Wilbanks, the so-called “Runaway Bride” who claimed to have been kidnapped and assaulted by a Hispanic man, but who had in fact voluntarily left her groom at the altar. Or the infamous Central Park Five case, in which five Black and Latino teenagers were arrested in 1989 for the brutal rape and assault of a white jogger in New York’s Central Park. Many people—including Donald Trump and African-American poet Sapphire (author of Push, from which the Oscar-winning film Precious was adapted)—jumped on the bandwagon falsely accusing the young men of the crime. More recently in Central Park there was Amy Cooper, a white woman who called 911 on black bird-watcher Christian Cooper, stating falsely that “there’s an African American threatening me and my dog.”

The many false sightings of Dorner is not unusual. One of the most famous cases of false sightings was the disappearance of a three-year-old British girl named Madeleine McCann, last seen at a resort in Portugal in May 2007. Her presumed abduction made international news, and photos of McCann circulated widely as police and the family hoped for tips from the public. This led to the girl being “sighted” in dozens of different places in Europe and around the world, from Belgium to Brazil, Australia to Africa, by eyewitnesses who reported seeing her. The case remains unsolved, though in recent weeks it’s been reported that a German man is the main suspect.

All this has implications for psychology and eyewitness reliability; if you tell people what to look for, any face or physique that is even remotely similar (large Black male, small blonde girl) can become a (false) positive identification. By some estimates, as many as one-third of eyewitness identifications in criminal cases are wrong, and nearly 200 people who were convicted of crimes based on positive eyewitness identifications were later exonerated through DNA evidence.

Dorner died in a shootout in the San Bernardino Mountains on February 12, 2013. Though he died before he could stand trial, Dorner left an extensive rambling manifesto complaining about racism, politics, and his perceived scapegoating when he reported another officer’s misconduct toward a mentally ill man. He quotes Mia Farrow and D.H. Lawrence; praises a long list of celebrities including Dave Chapelle, Bill Cosby, Tavis Smiley, and others (Charlie Sheen is “effin awesome”); he lists “THE MOST beautiful women on this planet, period” (including Jennifer Beals, Natalie Portman, Kelly Clarkson, Margaret Cho, and Queen Latifah); gives musical shout-outs (Eric Clapton, Bob Marley, Metallica, etc.); and so on. Recognizing that his mass murder spree would likely end in his death, he also lamented the fact that he would not live to see The Hangover 3.

He also addresses those he plans to kill and explains his motives: “Terminating officers because they expose a culture of lying, racism (from the academy), and excessive use of force will immediately change. The blue line will forever be severed and a cultural change will be implanted. You have awoken a sleeping giant. I am here to change and make policy. The culture of LAPD versus the community and honest/good officers needs to and will change. I am here to correct and calibrate your morale compasses to true north… I never had the opportunity to have a family of my own, I’m terminating yours. Look your wives/husbands and surviving children directly in the face and tell them the truth as to why your children are dead.”

The fact that police treatment of a mentally ill man was one of the triggers for the murder spree was not lost on many. Though it’s often claimed that the news media highlight mental illness primarily with white mass shooters and suspects, Dorner was widely described by officials and news media as mentally ill, with L.A. Mayor Antonio Villaraigosa stating that “Whatever problem [Dorner] has is mental” and February 9 Associated Press news article describing Dorner as “severely emotionally and mentally disturbed.” In fact the characterization of Dorner as mentally ill was so prominent that some even complained about it; one writer, Thandisizwe Chimurenga in the L.A. Watts Times (February 21, 2013), complained that “The Media Tried to Assassinate Chris Dorner [with descriptions] of ‘Mental Illness’.”

It is of course possible, even likely, that Dorner was both mentally ill and subjected to racial harassment in the LAPD. Given the rarity of African-American serial killers or mass shooters—let alone ones who are also police officers and leave a manifesto—it’s no wonder that Dorner is still discussed today.

A longer version of this piece appeared on my Center for Inquiry blog; you can read it HERE.