A woman who stole $206 worth of hotel-room paraphernalia told Buffalo, N.Y. police that her twin sister was the real culprit. As it turns out, the woman was not a twin, but does that trick ever work for real identical twins?

Absolutely. Newspapers are littered with stories of twins who confused police and prosecutors, either intentionally or unintentionally. The most notorious duo may be George and Charles Finn, former World War II pilots who were embroiled in a legal battle with the federal government in the 1950s over their claim to a C-46 transport plane. To prevent the feds from seizing the aircraft, one of the twins absconded with the plane and hid it in the Nevada desert. Although police eventually found the pair and the missing plane, the grand jury failed to indict either Finn, because an eyewitness couldn’t distinguish between them. The Finns’ physical similarities came back to haunt them in 1960, when police mistakenly arrested Charles in a hunt for George on charges unrelated to the plane controversy. Charles brawled with police through a federal building before authorities finally realized they had the wrong member of the “flying, fighting Finn twins.”

Decades later, police are still struggling with the same problem. In 2009, a pair of Malaysian identical twins was spared from execution when the judge ruled that prosecutors failed to prove which twin was the true owner a stash of narcotics. (Drug trafficking carries a mandatory death sentence in Malaysia.) In February of last year, eyewitnesses insisted that either Orlando Nembhard or his twin brother, Brandon, committed a murder outside an Arizona nightclub. The problem for investigators is that the witnesses disagreed on which twin was the gunman. After holding Orlando for months, prosecutors eventually dropped the charges, because they couldn’t prove beyond a reasonable doubt that either of the Nembhard twins committed the crime. Outraged relatives of the victim demanded that police “put [the twins] in a room and let them battle it out.”

Police haven’t tried that tactic, but they have employed a variety of methods to distinguish twins. Sometimes, circumstances clear up the confusion. In 1993, for example, a New York woman accused one of her twin stepsons of sexual assault and attempted murder, but his airtight alibi eventually led police to arrest his brother. When a set of twins repeatedly pulls the mistaken identity trick, authorities sometimes find scars or tattoos that help police on the beat tell them apart.

Identical twins have distinct fingerprints, because both genetic and environmental factors contribute to fingerprint formation. There are countless situations in which prints have helped police figure out they have the wrong twin. In May, police in Signal Mountain, Tenn. jailed a man for 36 hours and nearly had him extradited to Louisiana before fingerprints proved that the wanted man was actually the detainee’s (deceased) twin brother. Of course, fingerprint evidence isn’t always available or helpful. In the Nembhard case in Arizona, police haven’t recovered the murder weapon. As for the Finn twins, both brothers had left prints all over the cockpit of the stolen plane.

A new kind of genetic evidence may come to play a role in these cases. Epigenetics refers to chemical modifications to DNA that may change how genes are expressed. A study released earlier this year showed that the epigenetic profiles of identical twins differ at birth, presumably because of small differences in the twins’ uterine environments. While no prosecutor has yet used epigenetic evidence to distinguish a guilty twin from his innocent sibling, the findings should put would-be criminal twins on notice.

Got a question about today’s news? Ask the Explainer.