(CNN) -- Editor's note: This article contains graphic descriptions of what prosecutors say happened in the killing of a pregnant woman.
A Chicago woman accused of strangling a pregnant teen and cutting out her unborn baby had planned the killing for weeks, having first lied that she was expecting a child, and then using Facebook to find and lure her target, authorities said Friday.
Clarisa Figueroa, 46, strangled 19-year-old Marlen Ochoa-Lopez at Figueroa's Chicago home last month, then removed the teen's baby from her body and pretended it was hers, authorities say.
Figueroa and her daughter, Desiree Figueroa -- who police say helped in the strangulation -- were arrested this week after investigators found the teen's body in a trash can in Figueroa's yard Tuesday.
Clarisa and Desiree Figueroa, 24, were charged Thursday with first-degree murder and aggravated battery of a child less than 13 years old. Clarisa Figueroa's boyfriend, Piotr Bobak, 40, has been charged with concealing the death of a person and one felony count of concealing a homicidal death.
Police have said Ochoa-Lopez, a high school student, went to Figueroa's home at least twice this year after connecting on a Facebook group for mothers, where the teen accepted Figueroa's offer of baby items.
The baby boy is hospitalized in grave condition, and was on life support Friday, Chicago police said.
On Friday, assistant state's attorney James Murphy outlined for reporters the alleged actions Clarisa took to lure the pregnant mother.
According to prosecutors, Clarisa Figueroa's 20-year-old son Xander died in 2018. In October, she announced that she was pregnant, which was a surprise to her family, since she had her Fallopian tubes tied.
By December, Clarisa Figueroa had posted a picture of an ultrasound on Facebook, showing what she claimed was the baby she was carrying, Murphy said.
In February, Clarisa Figueroa posted a picture of a crib and baby's room to a Facebook page aimed at helping improve access to baby items for families in need, Murphy said. The next month, she posted on the page again, asking, "Who is due in May" and "Where is the May mama's at."
One of the people she connected with, Murphy said, was Ochoa-Lopez, who at that time was seven months pregnant. Clarisa Figueroa offered Ochoa-Lopez clothes for the baby and suggested they talk in a private message.
Murphy said that by April 1, Clarisa Figueroa had told her daughter that "she needed help killing a pregnant woman and taking a baby."
Around that time, Ochoa-Lopez first visited with Figueroa and Desiree, Murphy said. Desiree's boyfriend was also present.
At some point on April 1, they were all together, and Clarisa and Desiree "kept acting strange and on numerous occasions went into a separate room together," leading the boyfriend to tell Desiree that he would call police if they attempted to kill Ochoa-Lopez.
The teen then left the house, and Clarisa Figueroa and Desiree told the boyfriend that it was simply an April Fool's joke, Murphy said.
How prosecutors say the killing happened
On April 23, Murphy said, Ochoa-Lopez returned and sat on a couch. While Desiree Figueroa distracted the teen with a photo album, the elder Figueroa wrapped a cable around the teen's neck from behind, Murphy said.
When the teen was able to put her fingers between her neck and the cable, the elder Figueroa told her daughter that she wasn't doing her job, Murphy said.
Desiree "then stepped up and began to peel the victim's fingers from the cable one by one," Murphy said.
Clarisa Figueroa then got on top of the teen and strangled her for about four to five minutes, the prosecutor said.
When Ochoa-Lopez was dead, the elder Figueroa cut the teen's baby from her womb, and then called 911 and said she'd just delivered a baby that wasn't breathing, according to Murphy. Both were hospitalized, but Clarisa Figueroa showed no signs that might have suggested she had just delivered a baby, Murphy said.
Ochoa-Lopez's husband reported her missing on April 24, police say.
But it would take nearly three weeks before police unraveled what happened, culminating in investigators finding Ochoa-Lopez's remains in a trash can in the backyard of Clarisa Figueroa's home, authorities say.
The victim's family alleges police should have made the arrests much sooner, saying that investigators didn't immediately act on leads that the family and community members were providing.