The Missouri woman charged with kidnapping and killing a pregnant woman to steal her fetus used an offer of free baby clothes, posted on social media under a pseudonym, to lure her into a trap, authorities say.

Amber Waterman is now facing federal charges for allegedly taking Ashley Bush across state lines from Arkansas. And Waterman’s husband, Jamie, is charged as accessory, accused of helping her torch the 33-year-old victim’s body.

A criminal complaint reveals that investigators cracked the case with the help of Bush’s fiancé, cellphone pings, social media records—and a confession from Jamie Waterman.

Bush, who was 31 weeks pregnant, agreed to meet a woman using the name “Lucy Barrows” on Facebook who posted that she had “a bunch of baby items if any moms to be need them.”

After meeting at a library in Gravette, Arkansas, “Lucy” offered to hook up Bush with a job and her fiancé, Joshua Willis, drove her to a convenience store on Oct. 28 and made plans to pick her up there.

According to the complaint, when Willis returned he saw “Lucy” in a pickup truck driving away with Bush—who then did not pick up her phone, which was found days later on the side of the highway.

Police were able to find the Facebook profile for “Lucy Burrows” and trace the IP address to the Waterman home in Pineville, Missouri. They were also able to use Bush’s phone records to show that she traveled from Arkansas to Missouri.

On Nov. 1, detectives went to the Waterman home where Amber claimed that the day before she went into labor and delivered a stillborn child. Blood was found on the seats of a pickup truck that matched the description of the truck Willis saw Bush riding in before she went missing.

Two days later, investigators went to Jamie Waterman’s workplace, where he allegedly told them that the day before, Amber had confessed to killing Bush, only to quickly blame it on “Lucy.”

He allegedly said Amber led him to Bush’s body which “was clothed and was lying face-down next to a boat next to the house,” covered with a blue tarp, the complaint said.

Amber Waterman, the complaint says, removed a ring from Bush’s finger, and Jamie dragged the body to a fire pit. The couple allegedly doused the victim with gasoline and set a blaze that burned for an hour.

The two of them then are said to have driven the charred remains a short distance and dumped the body. According to investigators, Jamie Waterman led them to the dump spot, where the body was recovered.

Authorities say Bush’s fetus was found at a different location in Missouri.

Prosecutor Nathan Smith said it appears Bush was shot to death. He would not say how the fetus was removed from her body. “People do evil things,” Smith said. “That someone would prey upon a pregnant woman at her most vulnerable state is unimaginable. That’s the world we live in.”

News of Bush’s death and the arrest of the Watermans was especially chilling to an Arkansas mom named Emily Smith, who told KNWA that she had a close call with “Lucy Barrows.”

“I’m looking for maternity clothes since I am expecting, and Lucy Barrows commented on there and said she might have some,” Smith said.

“She had sent these pictures of just a couple of different pictures of these tops, and there was a pair, a couple of shorts. And then, she said we could meet, ” Smith said.

But Smith said the pictures were odd, and the Facebook profile was only two days old so she decided to pass.

“I’m thankful for the Lord. He was looking out for me, but I feel so bad for [Bush’s] family. It sucks that we have people in the world that sick,” Smith said.