Perhaps the most shocking element of Wednesday’s tragic events in Longmont, Colo., where a mother allegedly cut a baby from a 26-year-old pregnant woman, is that it wasn’t an isolated incident.

The details defy imagination. In early afternoon, a 911 call came into local authorities. “She cut me,” a voice said on the other end. “I’m pregnant.” Then shortly afterward, a black-haired woman named Dynel Lane arrived at a nearby hospital. Bundled in her arms was a baby. Lane said she had miscarried, and the baby soon died. But authorities said she was lying.

This inconceivable scenario makes more sense considered through the lens of an extremely rare but recurring phenomenon known among forensic scientists as Cesarean kidnapping or fetal abduction. It has roots in an earlier rash of kidnappings in the 1990s, when a string of baby snatchers descended upon North American hospitals and made off with infants. But as hospitals adapted to the troubling trend, installing more secure tracking measures, the phenomenon took a gruesome turn, experts said.

The urge to slice a child from another woman comes from a place of such desperation, such need, that desire solidifies into action, wrote Connecticut psychologist Theresa Porter, who has published a number of academic articles about infanticide and “neonaticide.” The women who do these sort of things aren’t insane, she said. Quite the contrary. They recognize a want — and act upon it.

“These women don’t simply want a baby; they need one in order to secure all the rewards and privileges of motherhood,” she wrote. “These women so desired the attention, care and love that society gives pregnant women and new mothers that they were willing to kill to obtain it.”

There’s no shortage of examples. In 2004, a Missouri woman killed a pregnant woman and then removed her baby. In 2008, a Seattle woman attacked a stranger who was pregnant and cut her live baby from her. In 2009, a Maryland woman was arrested after she attempted to cut a baby from another woman. A study in the Journal of Forensic Science discovered eight cases between 1987 and 2002. Porter counted 21 instances globally since 1987, saying the phenomenon is increasing. All of the “womb raiders,” as they’re sometimes called, are women.

“Unlike many homicides, in which a variety of different factors and influences make it impossible to generalize, the woman who commits this crime is someone whose feminine identity is very much wrapped up in her fertility,” Michael Welner, a forensic psychiatrist, told ABC in 2008. He was discussing a woman who removed a woman’s baby, killing her, then called 911 to inform them she had just given birth, but that her baby had died.

The women often fit into a fairly set profile, researchers said. Many of the women orchestrate an escalating series of ruses and deceptions. Most fake a pregnancy for weeks, if not months. Some even buy baby clothing, and two women, Jacqueline Williams and Effie Goodson, had baby showers. Such gambits attract the attention that motherhood — and especially pregnancy — confers upon a woman, Porter said.

“Children weren’t individuals with their own rights or destinies; they were means to an end, a way of garnering attention,” Porter said. “In the cases of cesarean kidnapping, the perpetrators are also seeking a role, that of a pregnant woman and new mother.”

The web of deception then widens to ensnare an unsuspecting woman who actually is pregnant, researchers said. Perpetrators deploy a trick in the form of an apparent act of generosity that belies malevolence. “For example, Josephina Saldana told Margarita Flores that she had a large supply of diapers she was willing to donate to the pregnant woman,” Porter found. “When Flores went to Saldana to pick up the supplies, she was killed and her fetus removed.”

Echoes of that anecdote are apparent in what police say happened in Longmont. The victim discovered a Craigslist advertisement to buy baby clothing. So she traveled to the home, where her baby was taken. Investigators told The Washington Post on Thursday they have  “a pretty good idea” what Lane’s motive was. “It would be something everybody would think,” a police spokesman said.

She wanted, perhaps, to be a mother.